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Immediate Care of the Wounded
Clifford C. Cloonan, MD, FACEP
COL (ret) U.S. Army
Associate Professor
Department of Military & Emergency Medicine
Uniformed Services University of the Health Sciences
Introductory Thoughts
“It will be tragic if medical historians can look back on the World War II period
and write of it as a time when so much was learned and so little remembered.”
Beecher H. Early Care of the Seriously Wounded Man. 1 , 2
“It is highly desirable that anyone engaged in war surgery should keep his ideas
fluid and so be ready to abandon methods which prove unsatisfactory in favour of
others which, at first, may appear revolutionary and even not free from inherent
danger.” 3 , 4
Bailey H, ed. Surgery of Modern Warfare. 2nd ed.
“Fight on, my men,” Sir Andrew says,
“A little I’m hurt, but not yet slain;
“I’ll but lie down and bleed awhile,
“And then I’ll rise and fight again.”
Ballad of Sir Andrew Barton, author unknown, c. 1550
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Introduction
This text represents a thirty year culmination of my thoughts about pre-hospital
combat casualty care.
My earliest introduction to this topic
came in 1973 when I attended the 91A
Combat Medic course in San Antonio
Texas, a necessary pre-requisite before I
could attend the 300 F-1 Special Forces
Medic course. It was mostly poorly
taught and improperly focused and fortunately I never had to take care of anyone in, or out of, a combat situation using only the knowledge gained in that
course. It was run by nurses and the
academic focus of the course was on
nursing care skills that were mostly irrelevant to pre-hospital combat casualty
care, presumably the realm of the combat medic. Some of the combat skills
instruction provided by veteran combat
medics with experience in the Vietnam
War was a notable exception.
Introductory Thoughts
knowledge of what I didn’t know and
youthfully confident in my skills and
knowledge of combat casualty care. I
was to never have the opportunity to
learn my shortcomings as a combat
medic since the Vietnam War wound
down faster than I completed my training. It was this training and experience
as a Special Forces medic that sent me
on the path to become a military physician.
What I learned in the ensuing years is
that most often:
•
•
•
•
•
The 300 F-1 Special Forces Medic
Course that followed was exactly the
opposite; it remains to this date the best
and most intense medical instruction I
have ever received. I learned more relevant medical information in the short
span of that course than I would ever
again learn in a similar time span. Upon
completion of that course I was left
wondering why it took physicians four
years of college, four years of medical
school and several more years of internship and residency training to learn what
I had learned in less than a year; I was
blessedly unencumbered with the
The simple answer is the right answer,
Well-performed basic techniques
are usually better for the patient
than more complicated and “sophisticated” techniques,
Conscious inaction is better than
mindless action,
Training is more important than
equipment, and
The day I graduated from the Special Forces Medic Course I was
“smarter” than I would ever be
again because mostly what I
learned later was all the things
that I didn’t, and would never,
know.
What I also learned in my nearly thirty
years in military medicine is that most
people believe that all relevant history
began the day they were born and therefore nothing much of use for the present
or the future can be learned from the
past. Nothing could be further from
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Introductory Thoughts
the truth -- there is actually very little
that is completely new in the realm of
military medicine. If you are looking for
the solution to a problem the first place
to look is in the past because there is a
good chance that someone else either
already solved the same or a similar
problem or at least was able to find out
what didn’t work.
What then is the basis for modern day
pre-hospital combat casualty care? It is a
composite of battle proven, albeit anecdotally supported, procedures and techniques combined with civilian EMS
standards of care (whether appropriate
to combat casualty care or not), some of
which are based upon well done studies,
many of which are not.
Throughout my career in military medicine I spent a considerable amount of
time as a trainer/educator; I observed
how people learn, what motivates them
to learn, what they are likely to remember, and what they are likely to forget. I
learned that it is much better to create
systems (educational or otherwise) that
take into account and accommodate
probable human behavior than it is to try
to shape or modify human behavior.
This text represents my best efforts to
glean from the pages of military medical
history and from such civilian prehospital care and other relevant studies
as have been done the evidence, weak
though it may be, that supports or refutes the performance of various procedures in a pre-hospital combat casualty
care environment.
I also learned that much, if not most, of
what is believed to be true has not been
proven true and further it is likely that
within my lifetime much of what I have
been taught will be proven to be false –
this as certainly been the case over the
past thirty years. I discovered that almost everything that is believed to be
true about pre-hospital combat casualty
care is completely unproven; this certainly does not mean it is false, just that
it has not been, and will likely never be,
proven true. The reason for this is because, for obvious reasons, there are no
randomized, double-blind, prospective
studies of pre-hospital combat casualty
care; and there are remarkably few such
studies of civilian pre-hospital care.
In the interest of full disclosure I admit
to the reader certain biases that I have
acquired as a result of the observations,
experiences, and education I have described above. One of these biases is
against teaching pre-hospital combat
casualty care providers complex and
potentially hazardous medical procedures even when there is no alternative
(e.g. cricothyrotomy); another is a bias
in favor of better training over better
equipment. I also have a bias that sometimes the most important thing is to
know what not to do and when not to do
it.
I independently observed that there is
strong psychological predisposition toward action over inaction among prehospital personnel, a predisposition that
is certainly characteristic of Special Operations medics/corpsmen. I had also
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
observed that when a procedure is
taught, particularly one that seems “heroic” (e.g. cardiac massage), that the
procedure will be performed much more
often than indicated. This observation
being epitomized by the often used,
tongue-in-cheek, comment by emergency medicine residents that the indication for a particular procedure they had
performed was that the RANDO criteria
had been fulfilled (Resident Ain’t Never
Done One).
I later found that these concepts had
been previously well-described by one
of the fathers of modern emergency
medicine, Dr. Peter Rosen, in a rather
obscure July 1981 publication, Topics in
Emergency Medicine, titled, “The
Technical Imperative: its definition and
application to pre-hospital care.” The
technical imperative and its implications
are defined and described in the early
portion of the “Airway” section in this
text and I would encourage readers to
obtain and read the original article for
greater detail (unfortunately it is hard to
find in most libraries – I eventually
found a copy in the library of the National Fire Academy in Emmitsburg
Maryland).
One of the reviewers of this material
suggested that it be re-written to appeal
to a larger audience, noting that it is presented in the manner of a textbook. I
was pleased by this comment because
that is exactly what I intended. The primary intended audience for my work
has been, from the beginning, military
medicine trainers/educators and medical
commanders who must make decisions
Introductory Thoughts
as to what should be taught and to
whom, and what material should be provided to those who provide pre-hospital
combat casualty care.
The material in this book was originally
written for inclusion in an unpublished
book, Combat Surgery, to be part of the
multi-volume “Textbook of Military
Medicine” series published by the U.S.
Army’s Office of the Surgeon General.
Unfortunately this book was never completed despite its obvious importance as
a key volume in any series on the subject of military medicine, and the whole
Textbook of Military Medicine project
has, I am told, been discontinued. Thus
as I finished my military career I was
left having done a considerable amount
of work for a book that, it seemed, was
never to be published.
So the situation remained until I was
contacted about a year ago by CAPT
(fmr) Mike Hughey MD, a fellow military medicine educator and friend. Mike
has a medical education website,
http://www.brooksidepress.org
that provides military medicine oriented
educational material. He inquired as to
whether I had any unpublished material
on the subject of military medicine that I
would like to get published? I replied
that I certainly did and provided him
with several megabytes of material that I
used throughout my career, some of
which I am pleased to see have already
been incorporated into his Website. I
also told him about this unpublished
work which he encouraged me to com4
Immediate Care of the Wounded
Clifford C. Cloonan, MD
plete and offered to provide some editing services as well as a place to publish
the material. Finally after more than four
years in the writing and thirty years in
the conceptualization here it is.
The commonly used ABCD approach is
utilized to frame the discussion of the
management of potentially life threatening problems in the pre-hospital combat
environment. Historical information and
current studies are incorporated to provide the reader an evidentiary basis
upon which to make decisions as to
what is likely to provide casualties benefit in a pre-hospital combat setting and
what is either likely to be ineffectual or
possibly harmful. Where it seems reasonable, based upon the available evidence, to offer what I believe is a best
practice I have done so, but mostly the
reader is given the available evidence
and is left to decide for him or herself
what materials, techniques, and procedures are most appropriate for prehospital combat casualty care providers.
Introductory Thoughts
feedback. Others too numerous to cite
individually have also reviewed this
work and have offered helpful suggestions and for their comments I am also
appreciative. Finally I would like to
thank my wife Ok Cha for her patience
and support while I labored on this work
to the exclusion of, at times, all else.
Acknowledgements
I would like to take the opportunity here
to thank those who made this work possible; most importantly Mike Hughey
who has provided a venue for the material and who has also provided considerable editorial support. I would also like
to thank Dr. Robert Joy, Professor
Emeritus at the Uniformed Services
University of the Health Sciences,
COL(ret) Ron Bellamy MD, Lt. Col.
John Wightman MD, USAF and COL
Candice Castro MD, for their detailed
reviews of my work and their helpful
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Introductory Thoughts
About the Author
Clifford C. Cloonan, M.D., FACEP
Colonel (ret)
Medical Corps, United States Army
undergraduate schooling at California Polytechnic State University at San Luis Obispo.
He majored in biochemistry and was in the
university's ROTC program, serving as the
ROTC cadet battalion commander during
his last year and receiving the George C.
Marshall Award. While in college he
worked as a registered nurse in a local hospital emergency department having used his
previous Special Forces medic training to
challenge the state registered nurse exam.
Dr. Cloonan is currently
a
staff
emergency
medicine physician at
Carlisle
Regional
Medical
Center
in
Carlisle Pennsylvania.
He is also an Associate
Professor at the Uniformed Services University of the Health
Sciences in Bethesda Maryland.
Prior to his retirement from the United
States Army in January 2004 Dr. Cloonan
was the Interim Chairman of the Department
of Military and Emergency Medicine at the
Uniformed Services University. From 1999
to 2002 he was the Consultant to the Surgeon General for Emergency Medicine and
he served as the Department of Defense representative to the National Registry for
Emergency Medicine Technicians from
2001 to 2004.
In the fall of 1979 he began medical school
at the Uniformed Services University of the
Health Sciences (USUHS), graduating with
honors in 1983. Following a transitional
internship at Brooke Army Medical Center
in San Antonio Texas and after a brief stint
as an instructor at the SF Aidman course, he
attended the Army's Flight Surgeon course
and spent the next 15 months in Korea as a
flight surgeon with the 43rd MASH.
Upon returning to the U.S. he attended the
Medical Officer Advanced Course and in
July 1986 he began his emergency medicine
residency at Madigan Army Medical Center,
Ft Lewis Washington, serving as one of the
chief residents.
COL Cloonan was born January 16, 1954 in
Boulder Colorado. He was an enlisted soldier assigned to the 10th Special Forces at
Fort Devens Massachusetts between 1972
and 1975. Initially trained as an infantryman with specialized training in light and
heavy weapons, he was later trained, and
spent most of his enlistment, as a Special
Forces medic.
After residency he was assigned to Tripler
Army Medical Center in Hawaii where he
served as a staff physician. In addition to
his regular duties he served in a volunteer
capacity in support of Joint Special Opera-
After his discharge as a Sergeant in August
1975 he joined the reserves and began his
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Introductory Thoughts
From July 1993 through June 1994, COL
Cloonan attended the US Marine Corps
Command and Staff College at Quantico,
Virginia, obtaining a Master of Military
Studies and graduating as the top army student. He then served as Division Surgeon for
the 2D Infantry Division in Uijongbu South
Korea following which he was Chief of
Emergency Medical Services at the 121
General Hospital in Seoul.
tions out of Ft Bragg North Carolina. In this
role he was in combat with the Forward
Surgical Team of the 44th Medical Brigade
at Howard Air Force Base, Panama during
Operation Just Cause.
Also while at Tripler he served as the head
of the hospital's Emergency Medical Response Team (E.M.R.T.) which was responsible for providing emergency medical
backup for Johnston Island, a major chemical weapons storage site in the Pacific. This
team was also responsible for providing regional military medical disaster assistance as
required. As chief of the E.M.R.T., COL
Cloonan was sent to Western Samoa in February, 1990 as part of a team to assess the
damage caused to that country by Cyclone
Ofa.
From August 1996 to January 1997 COL
Cloonan served as the Chief of the Emergency Department at Womack Army Medical Center, Fort Bragg, before becoming
Dean of the Joint Special Operations Medical Training Center. Prior to his second assignment to the Department of Military and
Emergency Medicine at the Uniformed Services University, from January 1977 to July
2000, COL Cloonan served as the Dean of
the newly established Joint Special Operations Medical Training Center within the
JFK Special Warfare Center and School at
Fort Bragg, North Carolina where all Special Operations enlisted medical personnel
within the Department of Defense receive
their training.
He was next assigned to the Uniformed Services University of the Health Sciences
(USUHS) medical school in August 1990 as
an assistant professor in the Department of
Military and Emergency Medicine. While at
USUHS from 1990-1993 COL Cloonan was
the course director for both the Combat
Medical Skills course and for the Introduction to Combat Casualty Care course and he
was Director of the Department’s Basic Science Division.
In addition to his teaching duties at USUHS
Dr. Cloonan also provided medical support
for several federal law enforcement agencies
involved in high risk law enforcement activities. In this capacity he provided medical
support for the FBI Hostage Rescue Team
during the Ruby Ridge standoff and during
the Branch Davidian Waco Texas incident
as well as medical support for numerous less
high profile local area SWAT missions.
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Introductory Thoughts
References
1
Beecher H. Early Care of the Seriously Wounded Man. JAMA. 1951;145(4):193-200
2
Henry K. Beecher, Father of the prospective, double-blind, placebo-controlled clinical
trial.
3
Bailey H, ed. Surgery of Modern Warfare. 2nd ed. Edinburg: E & S Livingston; 1942;
No. 1.
4
Hamilton Bailey, Reknown British Surgeon
Copyright 2007
The Brookside Associates, Ltd.
All Rights Reserved
8
Immediate Care of the Wounded
Clifford C. Cloonan, MD, FACEP
COL (ret) U.S. Army
Associate Professor
Department of Military & Emergency Medicine
Uniformed Services University of the Health Sciences
Airway
And when Elisha was come into the house, behold, the child was dead, and laid upon his
bed. And he went up, and lay upon the child, and put his mouth upon his mouth…and the
flesh of the child waxed warm…and the child opened his eyes
II Kings Chapter 4 verses 32-35, King James Version
“Of all the surgical operations which are performed in man for the preservation of life
by the physician, I have always judged to be the foremost that by which man is recalled
from a quick death to a sudden repossession of life, a feat which raises to the level of
Aesculapius; the operation is the opening of the asperia arteria [trachea], by which
patients, from a condition of almost suffocating obstruction to respiration, suddenly
regain consciousness, and draw again into their heart and lungs that vital ether the
air, so necessary to life, and again resume an existence which had been all but annihilated.” 1
Hieronymus Fabricius 1537–1619
Italian Anatomist and Surgeon
“Wounds of the face, when they do not implicate the brain, are not usually of a serious
character.”
Dr. Julian John Chisolm, Confederate Surgeon
Manual of Military Surgery, Chapter 8 Wounds of the Face p. 268
1
The mental image suggested by the term “gunshot wound of the face and jaws” invariably induces an emotion of sympathy, pity, or out and out revulsion. While numbering few
in the total of war casualties, they demand and deserve every conceivable effort in the
matter of medical care2
“Maxillo-Facial Injuries” by Major Henry B. Clark in
Forward Surgery of the Severely Wounded
(A History of the Activities of the 2nd Auxiliary Surgical Group)
World War II
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
Introduction
History of Airway Management
Having a patent airway is an essential prerequisite to life. Of this, there is no dispute. All textbooks on pre-hospital care
identify airway management as the preeminent skill in resuscitation because humans can only briefly tolerate anoxia; if
there is no airway, there is no life. Although there is no argument about these
fundamental facts, almost every other aspect of pre-hospital airway management
has become disputable, particularly in a
combat environment. The fundamental
questions in these debates are not whether
airway management is important, but
rather (1) how likely is airway obstruction,
which is amenable to and requires medical
correction, to be a problem in a prehospital military environment and, (2) after establishing that airway management
must be done,
For most of the history of man conditions
that cause complete airway obstruction
have resulted in death, there being little
that those in the medical professions could
do to change this result. This does not
mean that nothing has tried, occasionally
with some success. Most of the efforts
have been surgical but, particularly in
more recent history, not all. Stock, in his
“A Short History of the Development of
the Tracheostomy”,4 noted that the Babylonian Talmud (AD 352-427) makes reference to a case of swelling of the throat
(possibly referring to a peritonsilar abscess) saying that while a transverse division of the trachea will be fatal, a longitudinal section will not; suggesting that surgery had been tried for this condition, perhaps with some success. For some cases of
cynanche [infection/inflammation of the
upper airway with associated difficulty
breathing] surgical intervention has been
suggested and even tried since not long
after the death of Christ. Around 117 AD
Antyllus wrote that,
•
•
•
•
When should it be done;
Who should do it;
How should it be done; and
What equipment or medications, if
any, should be used?
“In cases of cynanche we entirely disapprove of the operation [tracheostomy] because the incision is wholly
unavailing when all the arteries [the
whole of the trachea and bronchi] and
the lungs are affected; but inflammation about the mouth and palate, and
in cases of indurated tonsils, which
obstruct the mouth of the windpipe
and the trachea is unaffected, it will
be proper to have recourse to pharyngotomy, in order to avoid the risk of
suffocation.”
How likely is airway obstruction to be a
medically correctable problem in a population of military patients; more specifically how likely is it to be a problem in a
population of combat casualties? Although
basic airway management should be part
of every pre-hospital care provider’s array
of skills, if airway obstruction is an extremely rare medical problem in the population of interest (living combat casualties), teaching intubation may result in
more problems then benefits -- especially
if done incorrectly or when not indicated.
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Thus, it is clear that tracheostomy was
being performed by western surgeons
some 2,000 years ago.4 In 1546 Antonio
Musa Brasavalo published the first account of a tracheostomy actually being
done,5 stating that, “When there is no
other possibility, in angina, of admitting
air to the heart, we must incise the larynx
below the abscess.” Fabricius (1537-1619)
described tracheostomy in detail, in glowing terms (see opening quote), but he
never performed the operation himself.1
By the early 1600’s, according to Stock,
tracheostomy appears to have been considered an acceptable procedure for the
treatment of upper airway obstruction.
Sanctorious (1561-1636) performed tracheostomy with a trocar and recorded
leaving the cannula in place for three days.
Nicolas Habicot performed four successful
tracheostomies in 1620; one on a 14 year
old boy who had swallowed a bag of gold
coins to prevent their theft whereupon the
bag became lodged in the esophagus causing partial airway obstruction.6
Marco Aurelio Severino (1580 – 1656), a
well-known anatomist and famous surgeon, performed tracheotomy several
times during the Naples diphtheria epidemic, this procedure having been previously described and recommended by
Guidi, Fabricius, and Sanctorius.7 Luckhaupt, in the German Journal, Laryngologie, Rhinologie, Otologiel,8 noted that
while the Arabian doctor Avicenna (9801037) described the first orotracheal intubation for the treatment of dsypnea, the
real beginning of endotracheal intubation
begins with this procedure being performed by obstetricians and lifesavers in
the 18th century.
In 1884, after four years of experimentation, intubation was first successfully performed by Joseph O’Dwyer (1841-98).7
Intubation of the larynx for croup was first
Airway
performed by Eugene Bouchut (1856),
who inserted a small thimble-like tube in
the larynx, but results were so poor that it
failed to replace tracheotomy. In 1880
McEwen is documented to have preoperatively intubated a patient to prevent the
aspiration of blood. Later, in 1900, Franz
Kuhn first performed routine intubation to
keep the airway clear during narcosis.8
In 1950, in the first volume of the Armed
Forces Medical Journal, Tarrow and
Knight describe the manufacture and use
of the modern, long-cuff, endotracheal
tube.9
During the Civil War, as a new way of
treating neck injuries that obstructed the
airway, surgeons performed tracheostomies, which were then referred to as
bronchostomies. As reported in Bollet’s
book, “Civil War Medicine, Challenges
and Triumphs”, they even left the tube in
for long periods if necessary.10 Bollet records that twenty of these procedures were
performed with seven survivors. Six of the
twenty were done to treat patients with
gunshot wounds and the other fourteen to
treat patients with diseases such as diphtheria and abscesses which threatened to
occlude the airway. In at least one instance
a silver tube was inserted as a tracheostomy tube that was later replaced by a
“double fenestrated cannula” which the
wounded soldier continued to wear six
months after his initial injury.
Frequency of Airway Obstruction in
Civilian Population
In a 6-month long French survey of outof-hospital emergency intubations in the
suburbs of Paris,11 there were 691 out-ofhospital endotracheal intubations; the most
common indication for this procedure being cardiac arrest (333/691 [48.2%]).
Among patients without cardiac arrest, the
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
most common indication was unconsciousness (198/358 [55.3%]). Only 9.3%
(64/691) of intubated patients were trauma
patients; of these, 22 (3.2%) had multiple
injuries, 31 (4.5%) had head injuries and
11 (1.6%) had burns.
Although it is unclear from the report
whether any of the patients with multiple
trauma also had head trauma (a common
indication for intubation in trauma patients), it is clear that at least half of all
pre-hospital intubated trauma patients
were intubated due to head trauma (and it
is almost certain that nearly all of these
had sustained blunt, not penetrating
trauma).
Frequency of Airway Obstruction in
Combat
What is the incidence of potentially survivable airway obstruction in combat
trauma patients? Estimates of the number
of combat casualties needing airway management (generally defined as those needing either intubation or a surgical airway)
are based upon data obtained from medical treatment facilities, not pre-hospital
data, which is entirely unavailable. This
likely represents only a small portion of
all casualties experiencing acute posttraumatic airway obstruction, however, because such casualties have, in the great
majority of instances, already survived for
more than an hour prior to reaching medical care.
As stated by Bellamy in “Combat Casualty Care Guidelines -- Operation Desert
Storm”12 in the Vietnam Wounding Data
Munitions Effectiveness Team (WDMET)
data13, only 1.3% of combat casualties
who arrived at medical facilities required
emergency airway management; and only
about half of these casualties (0.7% of the
total) had sustained traumatic airway in-
Airway
jury. Another 0.6% required airway control for ventilation due to severe neurological injury.
The incidence of casualties needing airway management upon arrival at a medical treatment facility in Vietnam (0.6%) is
quite similar to that occurring during Operation Desert Storm in 1990. Burkle et
al.14 reported that 2 (1.2%) of 164 combat
casualties admitted to the Khanjar NavyMarine Trauma Center had an airway obstruction that required tracheotomy. It
should be noted that these patients arrived
alive (probably after a lengthy evacuation)
without any pre-hospital surgical airway
having been established, so the degree of
urgency of the airway problem is unclear.
Bailey, in his World War II era text, “Surgery of Modern Warfare,”15 noted that,
“Wounds of the larynx are less commonly
seen than are those of the jaws and pharynx, because of their greater mortality”
and he notes that injuries to the cervical
spine and great vessels of the neck are
common and rapid causes of death in
casualties with penetrating neck injuries.15(p.808)[Chapter LXXI Wounds of the
Air Passages and Air Sinuses – Larynx,
Penetrating Wounds].
As is the case with other types of injuries
[see discussion about the Soviet incidence
of cervical spine injuries during WII in the
section on “Disability”] the incidence of
airway injuries in combat appears to be
affected by the type of combat. In World
War II it was noted that, “During the
hedgerow fighting in Normandy, there
was an unusually high incidence of maxillofacial injuries resulting from the close
type of combat and the necessity for the
men to expose their heads to see the enemy. These wounds were predominantly
caused by small arms fire and were characterized by being exceedingly severe and
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
not being associated with wounds elsewhere in the body.”16
It is also likely that the incidence of airway injuries in combat is affected by both
the type of armaments used and the frequency of body armor use. Weapons that
cause burn injury, for example, might create more casualties with airway injury that
is not immediately fatal (caused by progressive swelling) and thus might be amenable to medical intervention. Likewise
body armor, by reducing the number of
casualties killed outright by fatal wounds
to the thorax and abdomen, might result in
an increase in the number of airway injured casualties who survive initial injury.
Airway
Most of these patients had mid-face fractures caused by blunt trauma and the obstruction was caused by posterior displacement of the midface. Only 17 of
1,025 facial fracture patients (1.7%) developed airway compromise that required
emergency airway procedures. The authors of this study found that the rate of
endotracheal intubation in patients with
maxillofacial injury ranged from 2% to
6%. Because roughly 17% of seriously
traumatized patients have maxillofacial
trauma17 this means that somewhere between 0.4% and 1% of all civilian trauma
patients, most having blunt injury, require
intubation for airway problems resulting
from maxillofacial trauma.
It is worth noting that in this study the
number of trauma patients requiring airway intervention for maxillofacial trauma
is quite similar to that described earlier in
military series despite the differences in
patient populations. This is somewhat surprising because it would seem that patients
sustaining blunt trauma to the head and
neck would be more likely to present alive
and needing urgent airway management
than would those having sustained penetrating trauma.
Airway Obstruction by Tongue, from United States
Naval Hospital Corpsman 3 & 2 Training Manual
NAVEDTRA 10669-C June 1989
A large civilian series of patients with facial trauma17 found the causes of airway
obstruction in trauma patients to be the
following:
(1) obstruction by foreign body (e.g.
vomitus)
(2) obstruction by soft tissue (e.g.
tongue), hematoma, or avulsed parts
(3) disruption of the trachea
The other major indication for intubation
of civilian trauma patients is inability to
protect the airway, which occurs in severely head-injured or intoxicated patients. Unfortunately, these statistics from
a civilian population cannot be extrapolated to a population of combat trauma
patients because, as noted by Smith and
Bellamy, “Combat casualties do not have
the same propensity for blunt trauma, cervical spine injury, upper airway problems,
etc., as do civilian trauma victims.”18
The specific nature of combat-related airway injury was elucidated by Rehwald19
4
Immediate Care of the Wounded
Clifford C. Cloonan, MD
(in the Textbook of Military Medicine Part
IV, Surgical Combat Casualty Care: Anesthesia and Perioperative Care of the Combat Casualty, Chapter 3 Airway Management by Hecker and Kingsley20(p.57)). Using German data from World War II,
Rehwald reported the major causes of asphyxiation associated with injury to the
face and jaw as obstruction by the tongue
(40%), oropharyngeal tissue (29%), or soft
tissue (5%), tracheal compression (23%),
and aspiration of blood and vomitus
(3%).19
Fortunately, among those surviving long
enough to reach hospital level care the
mortality rate in maxillofacial wounds
tends to be low. In Fifth U.S. Army hospitals during World War II, there were only
6 deaths from this cause described in
1,450 battle casualty deaths.21
Indications for Airway Management
Management at Point of Wounding
If airway management is necessary it usually needs to be accomplished within a
few minutes of wounding if the casualty is
to survive. This fact has significant implications in the pre-hospital combat casualty
care airway management debate. Combat
casualties who develop an airway obstruction either immediately after or within a
few minutes of wounding will only survive if they themselves, or someone
nearby who can reach them immediately,
can clear their airway.
In general, airway clearing need not be
part of self-care training provided to all
combatants because individuals whose
condition permits them to do so will reflexively position themselves to allow the
most unobstructed breathing and to remove blood and secretions from the airway. However, at a conference conducted
at the end of the Korean War, it was sug-
Airway
gested that instruction be provided to maxillofacial-wounded casualties as to “how
to hold [their] head or how to lie on the
litter” because this may be lifesaving during the period of evacuation. It was also
suggested that “With bleeding about the
nose and mouth [such patients] should be
instructed to lie in a manner that will allow the blood to drain to the exterior and
not pass into the throat and cause aspiration and suffocation.”22
If maxillofacial wounded casualties are
unable to clear their own airway, then
someone else must perform the necessary
airway management procedure(s) or they
will die quickly. The number of casualties
who die within minutes of airway obstruction is not known because it is difficult to
determine the precise cause of death at
autopsy, particularly in those who have
sustained multiple injuries. Although it is
impossible to determine from the
WDMET data the exact number of soldiers who died on the battlefield in Vietnam due to acute airway obstruction prior
to medical intervention, autopsy results
suggest that this occurrence was uncommon.[(Bellamy RF, Colonel, Medical
Corps, US Army. Personal Communication, March 1995)]20(p. 56) Unfortunately,
autopsy data fail to reveal whether these
casualties died from airway obstruction or
with airway obstruction (exsanguination
and fatal neurologic injury being common
in patients with severe wounds to the head
and/or neck, as was noted earlier).
Prophylactic Airway Management
Of course, not all airway obstruction occurs at or near the time of injury. There
are instances, such as with inhalation injury or an expanding hematoma in the
neck, where the airway should be managed well before there is any significant
obstruction. There are also instances, such
5
Immediate Care of the Wounded
Clifford C. Cloonan, MD
as when a casualty becomes progressively
less able to maintain his or her own airway
(e.g. as with decreasing level of consciousness) where it is necessary for a care
provider to manage the casualty’s airway
at a time considerably past the time of initial injury.
This type of patient is not uncommon in
civilian pre-hospital care where closed
head injury (expanding subdural or epidural hematoma) and drug and/or alcohol
intoxication is usually the cause. Neither
of these conditions, however, is common
in battlefield casualties. Another category
of patients needing airway management in
the civilian pre-hospital setting includes
those with disease processes such as severe asthma, cardiac problems, or severe
pneumonia, which are rarely found in the
pre-hospital battlefield patient population.
It is worth noting, however, that individuals with a prior history of childhood
asthma are no longer precluded from
enlistment so the frequency of respiratory
emergencies from this cause is likely to
rise in the future.
Responsibility for Airway
Management at Point of Wounding
As described in the Anesthesia volume of
this series,
Many of the battle casualties who require immediate airway intervention
will not survive to be evacuated from
the site of injury to the field hospital
level without first receiving airway
control. For these casualties, airway
intervention must take place in the
first or second echelons of care….
Therefore, medics, physician assistants, and physicians providing care
at the first and second echelons must
be able to provide early airway management. 20(p.57)
Airway
Because airway obstruction must be alleviated within minutes or the patient will
not survive, moving an airway obstructed
patient to someone who can clear his or
her airway is not an effective option in
most instances due to the associated inherent time delay. From a training perspective, this means that better training in basic airway management for every soldier,
during basic training and within the combat lifesaver program, is more likely to
save lives than will advanced airway management training for any higher, and less
immediately available, levels of medical
care (See surgical airway section, below,
for a discussion of training considerations
for advanced airway procedures).
Decision Making in
Airway Management
It is reasonable to question the efficacy of
the standard civilian approach to prehospital airway management especially if
it is to be applied to a population of combat casualties. Every intervention has consequences. Actions taken that might provide benefit in one situation might cause
more harm than benefit in another. Airway
management of the potentially cervicalspine injured patient is an example where
the civilian approach may be inappropriate
in a combat setting.
Standard Advanced Trauma Life Support
(ATLS)23 and Emergency Medical Technician (EMT) training emphasizes that
because patients with head and neck injuries (i.e., injuries above the clavicle) have
a higher probability of unstable cervical
spine injury, the cervical spine must be
stabilized in all such patients. This means
that they are to be placed on a backboard,
a rigid cervical collar applied, and their
heads and bodies strapped and taped to the
backboard. The airway of such “pack6
Immediate Care of the Wounded
Clifford C. Cloonan, MD
aged” patients is put at risk in the following ways:
•
•
•
Being forcibly held in a supine position makes the patient extremely
dependent upon someone else to
clear his or her airway in the event
that vomitus, blood, tissue, or other
debris cause obstruction;
Obstruction of the airway by the
tongue is much more likely in the
supine position
The cervical collar, even if properly
applied, and it often is not (and improperly applied may actually
physically obstruct the airway),
forces the mouth closed.
Airway
hospital medical education. The very fact
that they are basic and relatively simple to
perform tends to cause healthcare workers
to undervalue their importance. For this
reason, and others, pre-hospital care providers who are taught more advanced airway skills often go directly to the use of
advanced procedures even when more basic techniques would have sufficed if
properly performed; occasionally with
tragic consequences. The following case
provided from civilian EMS literature, is
illustrative:25
A 17 year old girl was an unrestrained
passenger of a vehicle that struck a
stationary truck. She was eventually
found to have sustained a liver laceration, right pulmonary contusion, LeForte II/III and mandible fractures,
and an acetabular fracture -- a CT of
the head revealed no intracranial
hemorrhage.
Despite these concerns, because blunt
trauma is much more likely than penetrating trauma to produce an unstable cervical
spine24, and because there are usually adequate medical personnel with appropriate
equipment to keep the airway clear, this is
probably, nonetheless, appropriate for the
majority of civilian trauma patients. Because none of these circumstances are
likely to be present in forward combat areas, however, such management carries
substantial risk with little hope of benefit.
When the possibility of an unstable cervical spine is present in a combat casualty
(e.g. a motor vehicle accident, fall from a
height) and when medical vigilance can be
provided and sustained to ensure that the
airway remains clear, Advanced Trauma
Life Support guidelines for civilian management of possible cervical spine injury
remain reasonable and appropriate in the
combat setting. (A detailed discussion of
patient packaging for suspected spinal injuries appears in a following section on
“Disability”)
Citing instability of “unstable” facial
fractures as their justification, the onscene paramedics elected to intubate
the patient [perhaps the patient developed respiratory difficulty when she
was placed in a supine position and
secured on a backboard for cervicalspine control].
Several unsuccessful attempts were
made to orally intubate the patient
without administration of a paralytic
agent. When the aeromedical team arrived they described the patient as
“awake, alert, and oriented X 3 with
full recall of the accident.” Citing
again “deformed” and “unstable facial bones” and “respiratory difficulty” the aeromedical team elected to
perform rapid sequence intubation of
the patient using etomidate and succinylcholine. This despite that fact
that there was no documented drop in
Unfortunately simple and basic lifesaving
airway management techniques are often
not well emphasized or taught in pre7
Immediate Care of the Wounded
Clifford C. Cloonan, MD
oxygen saturation and vital signs remained unchanged. Furthermore their
notes reflect that the patient had, “A
normal mental status, and “clear
speech.”
Endotracheal tube placement was
confirmed by appropriate breath
sounds [notoriously unreliable under
the best of circumstances-- which this
was not]. No end-tidal CO2 was recorded. The record then reflects the
endotracheal tube became “dislodged” while it was being secured
with ground crew assistance. At this
point, “multiple” unsuccessful oral intubation attempts were made (no
number recorded by the crew).
The patient’s oxygen saturation fell
from 96% to 88% and then to 74%
over a period of 8 minutes. Bag-valvemask ventilation was reportedly difficult so a cricothyrotomy (unsuccessful) was attempted. Cardiac arrest occurred 5 minutes prior to ED arrival.
A final pre-hospital attempt at oral intubation was successful. In the emergency department the patient was
noted to be in a rhythm of pulseless
electrical activity; this was successfully treated with return of spontaneous circulation. Unfortunately in the
intensive care unit, multi-system organ failure ensued, brain death was
declared; 55 hours after admission
life support was withdrawn. Tragically, a trauma review panel concluded that all of the patient’s initial
injuries were survivable and death resulted from hypoxia due to failed airway interventions.25
Airway
The Technical Imperative
In July 1981, Rosen et al. introduced the
concept of the “technical imperative,” and
applied it to pre-hospital care (although
this concept actually applies to all levels
of care).26 First, the authors noted the psychological obstacle that exists in emergency medical personnel to inaction;
…there is a pervasive theme [in emergency care]…one of action orientation, that is, of specific technical intervention…. [B]efore addressing the
individual procedures, the psychological basis underlying the performance of technical acts must [should]
be considered.…[W]e select for, and
demand, an aggressive, actionoriented psychological profile in our
personnel. The consequence of this is
that the hardest task for any good
paramedic, nurse, or emergency physician to perform is inaction.
Next, they described the technical imperative as follows:
If a procedure is taught, it will be used
with a frequency greater than its indications. [Further], every procedure…has a cost that must be assessed as a complex therapeutic ratio,
the deficit to the patient produced by
not performing the procedure versus
the deficit produced by performing the
procedure “improperly” or performing it properly but unnecessarily.
Even when medical procedures are properly performed and done only for valid,
indicated, reasons, there can be lifethreatening complications. Airway injury
during airway management even in the
best of circumstances, such as endotracheal intubation performed by anesthesiologists/anesthetists during general anes8
Immediate Care of the Wounded
Clifford C. Cloonan, MD
thesia, is a significant source of morbidity
for patients.27 Although most of these injuries are not life-threatening, some, such
as pharyngeal and esophageal injury, can
be. Esophageal injuries are more severe
than all other types of airway injury combined and represent a significant portion
of intubation-induced mortality.28-31
Airway Management Procedures
The ideal approach to emergent airway
management of a combat casualty in a
given set of circumstances depends upon
the following:
•
•
•
•
•
•
Degree of patient acuity
Level of training and experience of
the pre-hospital care provider(s),
Tactical and environmental situation,
Mode and distance of evacuation,
Number of other casualties present
Availability of medical personnel to
manage the patient after the definitive airway management procedure
has been performed.
When managing airway problems in combat environments pre-hospital personnel
should consider using the least invasive
techniques first, and refrain from using
advanced procedures until they have balanced the inherent risks against the anticipated benefit. The least invasive procedures such as proper positioning, maneuvers such as the head-tilt or jaw-thrust,
and clearing of the airway of secretions or
debris, carry the least risk to the patient
and can be most easily taught and sustained. For the majority of patients needing airway management in the pre-hospital
combat environment, these procedures are
usually adequate.
Airway
Basic Airway Management
As described by Bailey in World War II,
in managing patients with maxillofacial
wounds, “The immediate aim is to save
the life of the patient.” This means maintaining the airway, controlling hemorrhage, and preventing blood and other
things from entering the trachea and causing airway obstruction.15(p.811) As noted
above, these tasks can usually be effectively achieved by timely and effective
application of a few simple, basic, procedures.
Body Position
During World War II the following guidance regarding proper litter evacuation of
casualties was provided by the Surgical
Consultant in the European Theater of
Operations:
In the litter evacuation of fresh maxillofacial casualties, adequate attention
occasionally has not been paid to the
proper position for such cases. Improper position may result in fatality
during evacuation. Instructions on this
matter should be provided all personnel handling fresh casualties. Severe
cases should be arranged in a prone
position on the litter with the head
supported by blankets. Such position
gives the greatest assurance that the
airway will be maintained and provides against the danger of aspiration
of blood and oral secretions.32
Also in World War II, Henry K. Beecher
noted that among “common but grave errors” was the “transporting of patients in a
face-up position instead of face-down,
when they have pharyngeal wounds.”33
And the WWII history of the 2nd Auxiliary
Surgical Group notes that “Maintenance
of a clear respiratory tract may be accom9
Immediate Care of the Wounded
Clifford C. Cloonan, MD
plished by…extension of the tongue, and
by postural drainage.”34 Earlier, in the
Spanish Civil War (1939), Douglas Jolly,
a British military surgeon, noted that following emergent treatment, patients who
have sustained buccal wounds should be:
1) Placed in the prone position with a
folded coat or haversack under the
chest and their heads turned to the
side
2) Under continuous surveillance by
an orderly during evacuation and
in the event that hemorrhage occurs from the face or pharynx
3) Kept by the orderly in the prone
position and the orderly must
swab the pharynx to prevent aspiration of blood into the glottis.35
Supporting these earlier observations is a
recent study36, 37 of poisoned comatose
patients that demonstrated that the prone
and semi-recumbent (head-down) positions are associated with a reduced incidence of aspiration pneumonia.
In the Anesthesia volume of “The Textbook of Military Medicine”, Hecker &
Kingsley note that,
Casualties with facial lacerations
(common in penetrating head trauma)
often present with copious bleeding
that may contribute to airway obstruction. Relief of obstruction can frequently be obtained with gentle suctioning and if possible, by allowing
the casualty to sit forward rather than
supine. Gentle forward traction on an
unstable, fractured mandible may also
relieve simple obstruction.” 20(p. 74)
As noted above, World War II data indicate that asphyxiation associated with facial and jaw wounds was due to prolapse
of the tongue into the pharynx in 40% of
Airway
cases and to aspiration of blood and vomitus in 3% of cases.20(p. 57) Given that some
of the other causes of asphyxiation described in these data may have been correctable with simple airway maneuvers
and/or patient positioning, it may be surmised that at least half of all cases of
death from asphyxiation after maxillofacial trauma may be preventable with basic
airway maneuvers and proper patient positioning.
At, and forward of, the Battalion Aid Station or similarly equipped and staffed
treatment post, it is difficult to do more
than the most basic of procedures so the
maxillo-facial wounded casualty should be
transported as soon as possible to a better
equipped and staffed facility. According to
Bailey, “Obvious bleeding points should
be controlled…however, if the compression has the effect of increasing the
amount of inhaled blood, it must then be
decided to allow free external escape, for
fear of asphyxiating the patient…If a suction pump is available, its use will be of
great benefit in dealing with these complications.”15
Interviews of paramedics by Karch et al.
found that although failure to intubate
trauma patients in the field was most
common in gagging or combative patients,
in nearly a quarter of survivors, inability
to intubate was due to blockage of the
airway with blood or vomitus.38
Even the ATLS course23, which strongly
advocates rapidly obtaining a definitive
airway, makes it clear that not all patients
with airway trauma require immediate
advanced airway management. Even patients who have sustained massive trauma
to the upper airway can often be managed,
at least initially, using the basic airway
management techniques described above.
The patient shown below in Fig 1 is such a
10
Immediate Care of the Wounded
Clifford C. Cloonan, MD
patient. Note that this patient is not intubated and does not have a surgical airway.
Only suctioning and positioning were used
to keep this patient’s airway clear in the
emergency department.
Frequently, at the point-of-wounding, patients with such injuries have already positioned themselves to optimize their airway
and if able to do so will continue to protect their airway unless interfered with by
later arriving medical personnel. Sometimes well-intentioned pre-hospital personnel, while attempting to minimize the
risk of injury to a potentially unstable cervical spine, will interfere with the patient’s efforts to maintain a patent airway,
thereby doing more harm than good. Often
patients with massive facial trauma do
best when allowed to sit up and lean forward, allowing blood, secretions, teeth,
and soft tissue to be kept out of the upper
airway.
Airway
This author personally recalls the case of a
civilian patient with blunt facial trauma
who developed airway obstruction as a
direct result of such well-intentioned cervical spine management. The patient had
been struck in the face with a baseball bat
fracturing both sides of his mandible and a
number of teeth. When EMS arrived the
patient was on his hands and knees with
blood dripping from his mouth, spitting
out teeth and in pain but not in any respiratory distress. EMS personnel, following
their guidelines, placed the patient in a
supine position, with his cervical spine
immobilized, on a backboard. When the
patient arrived in the emergency department he was having marked difficulty
breathing due to prolapse of his unsupported tongue into the posterior pharynx;
this was alleviated with suction and outward digital traction of the jaw. In this
instance well-intentioned EMS intervention almost killed the patient.
Figure 1. This man was the victim of an attempted
assassination by shotgun blast to the head (turned
head at moment shot was fired). The patient was
responsive on ED admission. Only suctioning and
positioning were used to keep this patient’s airway
clear in the ED. A surgical airway was placed in an
operating room. Patient lost one eye and had his
face reconstructed. Photo provided courtesy of Dr.
Peter Rhee, military trauma surgeon
11
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
Administration of morphine to combatants with facial wounds - It was Maj.
Jolly’s opinion, during the Spanish Civil
War, that morphine must be given early
in all such cases, preferably intravenously so as to produce an immediate
effect.35(p.137) But just a few years later,
in World War II, Bailey recommended
that morphine be avoided in maxillofacial wounded casualties “owing to its
depressing effect on the cough reflex
and respiratory centre” because, “the
patient’s life may depend on his ability
to protect his airway by coughing.”15 On
this same issue the WWII history of the
activities of the 2nd Auxiliary Surgical
Group noted that, “Due to mechanical
respiratory difficulties in many of these
cases it is wise to give morphine sparingly and in no case is it advisable to
give more than ¼ grain (15 mg) every
four hours.”34 Interestingly today even
this smaller amount of morphine is
higher than most pre-hospital personnel
are comfortable with administering or,
in some instances, are allowed to give.
dures. All of these factors decrease the
likelihood of successful performance of
definitive airway procedures. Under
these circumstances, even if definitive
airway management can be successfully
accomplished without serious complications, most intubated patients not only
are completely dependent upon others
for every element of their survival but in
the majority of situations they must be
continually ventilated. In the prehospital combat environment, this creates a difficult, if not impossible, logistical challenge during evacuation to
higher levels of care.
Advanced Airway Management
There is little dispute that when a patient
has either significant or impending airway obstruction, establishing a definitive airway with a cuffed tube is ideal.
Depending upon the circumstances, this
is appropriately accomplished either by
endotracheal intubation or by establishment of a surgical airway. The prehospital environment is, of course, a
less-than-ideal surgical venue, being
characterized by varying degrees of
chaos; imminent danger; environmental
extremes; inadequate lighting; inadequate equipment; and healthcare providers who are either untrained in, or at
least relatively inexperienced in, the performance of advanced airway proce-
Indications
Emergency airway management requiring advanced airway procedures in the
setting of trauma is most often indicated
in cases of severe head injuries.
WDMET data indicate that more than
half of the 1.3% of combat casualties
requiring emergency airway management had severe head injuries20(p. 56) [It
should
be
noted
here
that
Bellamy’s “The Nature of Combat Injuries and the Role of ATLS in their Management” and the Anesthesia volume of
the Textbook of Military Medicine20(p.56)
have the incidence of head injuries and
traumatic airway injury as an indication
of intubation reversed (although both are
so close – 0.6% and 0.7% -- that it is
probably not a significant error)]. In a
1997study of pre-hospital cricothyrotomies done by physicians in Israel, cricothyrotomies were done on only 3.3% of
all patients requiring pre-hospital airway
procedures and, of these, roughly twothirds had sustained penetrating trauma
39
(Israel may be somewhat unique
among developed countries because of
its disproportionately high percentage of
patients sustaining penetrating trauma).
12
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
Cricothyrotomies were successfully
completed in 26 of the 29 study patients
(89.6%), but overall mortality in the
study was 55.1%.
quence intubation, with 26 (84%) of the
desaturation episodes occurring in patients whose initial SpO2 value was
greater than or equal to 90%. Therefore,
patients given rapid-sequence intubation
experienced more hypoxia, the very
condition intubation is intended to prevent, than those managed with basic
airway techniques and assisted bagvalve-mask ventilation. The extent and
duration of desaturation were significant
in several of these cases and six (19%)
of the patients experienced marked bradycardia (defined here as a pulse rate of
< 50 beats per minute so presumably a
heart rate between 50 and 60 was not
considered to be “marked”).
Cuffed Endotracheal Tube with Stylette
Efficacy
Unfortunately in many, if not most,
cases, if endotracheal intubation can be
performed on a severely head injured
casualty without the use of paralytic and
sedative drugs (i.e., when the patient is
unresponsive, flaccid, or has no gag reflex) the likelihood of survival is very
low. This means that, in most cases, if
intubation is to help save patients with
survivable injuries, rapid sequence intubation must be done. Some civilian
emergency medical systems authorize
paramedics to perform rapid-sequence
intubation but a recent study by Dunford
et al. 40 raises serious doubts about the
safety of this procedure when performed
by pre-hospital personnel in an out-ofhospital setting.
Perhaps the most unsettling finding of
this study is that the paramedics performing the rapid sequence intubation
described the procedure as "easy" in 26
(84%) of 31 patients who experienced
desaturation. Spaite and Criss41 note that
these findings make the near absence of
reported significant complications in
other studies of pre-hospital rapid sequence intubation seem implausible;
they point out the following:
•
In this study the incidence of desaturation and pulse rate reactivity during
paramedic rapid sequence intubation in
54 patients with severe head injury
(Glasgow Coma Scale ≤8) was determined.40 Thirty-one (57%) patients experienced desaturation during rapid se-
•
13
The Dunford study, despite being
carried out in a busy, metropolitan
EMS system with substantial
medical oversight and involving
experienced paramedics, had a
staggering rate of significant desaturation during rapid-sequence
intubation, suggesting that an
even higher rate could be expected under less optimal circumstances
The fact that the paramedics assessed the rapid-sequence intubation procedure as “easy” despite
the 84% associated morbidity
suggests that other EMS studies
that rely on self-reporting of com-
Immediate Care of the Wounded
Clifford C. Cloonan, MD
plications very likely suffer from
significant under-reporting.
In a study of field-intubated trauma patients by Karch et al.,38 in which roughly
one-third had sustained gunshot
wound(s), the following findings were
noted:
•
•
•
•
•
Intubated gunshot wounded patients were the least likely of all
intubated patients to survive to
discharge
All surviving intubated trauma patients had head and/or facial injuries
No patients with truncal injuries
who required intubation survived
Only slightly more than half of
these patients were successfully
intubated in the field
Field intubation was three times
more likely to be associated with
nosocomial pneumonia than was
hospital intubation (almost certainly due to a high rate of associated aspiration)38
Airway
performed on Israeli military trauma
victims the failure rate of the first intubation attempt could exceed 40%.45
Based on this preliminary finding the
authors conducted a study to determine
which factors might raise the risk of
problematic intubation in soldiers. They
concluded that difficult field intubations
in soldiers is most probably unrelated to
anatomical causes (e.g., high Mallampati score), and is more likely due to
“complicated scenarios and deficient
skills….”44
Thus much of the literature does not
support intubation of combat casualties
specifically showing that
•
•
Early studies show that field intubation
is infrequently used in civilian trauma,
perhaps because of its high failure rate.
In a 1983 study of pre-hospital endotracheal intubation in Boston, only 16.2%
of 178 field-intubated patients were
trauma victims (e.g., blunt and penetrating injury, drowning and asphyxiation)
42
In a 1984 study of field intubation in
Pittsburgh only 4% of attempted intubations were on trauma patients and of
these almost one-third were unsuccessful.43
•
•
This failure rate in trauma patients was
dramatically higher than the less than
10% failure rate cited in later studies.44
Abraham et al. reported that based on
unpublished data of field intubations
•
14
Pre-hospital intubation is rarely
required for trauma patients (civilian or combat); the great majority
of combat casualties who require
intubation do so because they are
to undergo general anesthesia and
subsequent surgery;14
There are virtually no survivors in
intubated trauma patients who
sustain other than head and/or facial trauma
Blunt trauma to the head, neck, or
face, which is proportionately
much more common in civilian
settings than in combat, is more
likely than penetrating trauma to
produce a patient who will benefit
from advanced pre-hospital airway intervention
A sizable portion of trauma patients with airway obstruction
have a problem that is correctable
with suctioning, basic airway maneuvers and/or proper positioning
of the patient
There is a high incidence of failure when intubating trauma patients, even in systems where the
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
•
overall intubation success rate is
high
Finally, it is important to recognize, as
Karch et al.38 point out, that “Neither the
success nor the complication rate for
field intubation of trauma patients is
known with any certainty.”
•
Complications
Despite numerous case reports in the
literature, including reports during routine anesthesia care, pharyngoesophageal perforation is an under-appreciated
complication of tracheal intubation27
that may cause life-threatening injury.
Overall mortality after esophageal perforation is high (25%), even with rapid
diagnosis and treatment.45 Difficult intubation, emergency intubation, and intubation by inexperienced personnel are
risk factors for pharyngoesophageal perforation.45
Even if military pre-hospital medical
personnel are trained in advanced airway procedures, it is likely that a substantial number of intubation attempts
will be unsuccessful. Despite the fact
that civilian paramedics are well trained
in airway management and frequently
respond to patients in respiratory distress, in some systems as many as 25%
of endotracheal tubes inserted by prehospital personnel in urban emergency
medical systems are misplaced.46 Although a number of studies showing
high intubation success rates for civilian
pre-hospital personnel have been published, it is unlikely that such rates could
be obtained by military pre-hospital personnel even if there were an indication
for the procedure. Reasons for this are
as follows:
•
•
Paramedics in emergency medical
systems that report 90+% success
rates for intubation generally have
relatively frequent opportunities
to perform indicated intubations
These paramedics are also, in
most instances, part of an emergency medical system that has an
intubation skills sustainment requirement of performance of a set
number of intubations under the
supervision of an anesthesiologist
on an annual basis
There is also reason to suspect, in
a number of instances, that the actual intubation success rates in civilian emergency medical systems
studies are not actually as high as
reported (Mizelle et al. note that
in many reported series, intubation success is defined by the intubator and is unconfirmed by an
independent observer utilizing an
objective measure such as capnographic waveform analysis25)
Trauma, not disease, is the predominate cause of airway difficulties in a combat setting and, as
was previously noted38, the intubation success rate in trauma victims, even by experienced paramedics, is significantly lower than
the average rate.
According to a 1987 study, anesthesia
residents require a mean of 58 intubations before they become successful
more than 90% of the time, and require
more than 90 intubations to be successful more than 95% of the time.47 If this
learning curve applies to highly trained
physicians working in a generally wellcontrolled, well-lit, well-equipped hospital environment, how can pre-hospital
personnel with less training, less experience, and operating in an uncontrolled
and suboptimal environment have equal
15
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
or better success rates?25 It is also likely
that serious complications are relatively
common following pre-hospital intubation, particularly when the intubator is
inexperienced, as most military prehospital providers are; and especially
when the procedure is done in a chaotic
combat environment. Dr. Ron Walls, a
recognized expert in difficult airway
management, notes that many factors
increase the difficulty of intubation, including the following, many of which
are present in trauma victims in a prehospital setting:
tion and airway protection. Thus, it
may no longer be acceptable to simply
arrive at the hospital with an endotracheal tube in place; instead, the
means by which the ETI [endotracheal
intubation] was achieved and the adverse physiologic conditions imposed
upon the patient during the procedure
may be more important. In fact, these
results force us to ask whether early
ETI itself is beneficial at all in any patient subsets.
•
•
•
•
Inability to achieve the necessary
alignment of the geometric axes,
Limitations to oral cavity access,
Interference with the passage of
an endotracheal tube, and
Distortion of normal anatomy.48
Further compounding these difficulties
is the fact that trauma patients are often
uncooperative or even combative due to
pain, hypoxia, and/or brain injury. All of
these factors, combined with others
common in combat situations such as
extreme cold or heat, poor visibility (due
to darkness, sand, etc.), influx of large
numbers of patients at once, incoming
enemy fire, and need for rapid extraction
to name a few, may make intubation
difficult, if not impossible, even for individuals who are experienced in airway
management.
In 2004 Wang, Davis, Wayne, and Delbridge49 did a thorough review of the
evidence supporting pre-hospital rapid
sequence intubation. They came to the
conclusion that,
A growing body of evidence suggests
that invasive airway management
comes with a price that may outweigh
any benefits with regard to oxygena-
Establishment of a Surgical Airway
Although intubation is indicated in
some cases, the majority of patients with
airway obstruction resulting from combat-associated trauma can be managed
successfully with simple positioning
and/or suctioning; some, however, require surgical intervention. In many of
those who do not respond to basic airway management techniques, endotracheal intubation is not possible for the
reasons previously described.
For this reason the only advanced airway technique taught by medical educators for the British Special Air Services
to their highly specialized medics is a
surgical airway; they do not teach endotracheal intubation. This is a logical
decision given the epidemiology of
combat-associated airway obstruction. It
should, however, be noted that there is
no evidence indicating that this approach saves more airway-obstructed
casualties than intubation or even just
basic airway maneuvers, or that total
mortality (including those associated
with inappropriately performed or unindicated surgical airway procedures) is
reduced.
16
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Clifford C. Cloonan, MD
Airway
Cricothyrotomy
Training
Because the “can’t intubate, can’t ventilate” circumstance, although quite rare,
does occur, should pre-hospital personnel be taught to establish surgical airways as a last-ditch method? A recent
panel discussion involving emergency
medicine physicians, trauma surgeons,
and combat medics conducted at the
Special Operations Medical Association
annual conference in Tampa Florida
(December 9, 2003, moderated by this
author)50 addressed this question but did
not reach a consensus.
A number of the panelists stated that all
military pre-hospital personnel who are
taught and authorized to perform endotracheal intubation should be taught
and authorized to perform cricothyrotomies as well. There was consensus,
however, that those authorized to perform cricothyrotomies must be properly
trained, their competency effectively
evaluated (a good simulator is needed),
and their competency sustained over
time.
It is important to note that both the initial and sustainment training needed to
achieve and maintain competency in this
procedure are relatively expensive in
time, human resources, and equipment.
Given the rarity of treatable lifethreatening airway problems in combat
casualties that require a surgical airway,
it is worth asking whether these resources might be better allocated to
more pervasive problems, such as ensuring highly effective hemorrhage control.
Cricothyroid Membrane
Thyroid Cartilage
Training to establish a surgical airway is
problematic because it is very difficult
to replicate the circumstances, anatomy,
and pathophysiology of a combat casualty with a traumatically obstructed airway. In reality, patients with complete,
or near-complete, obstruction of the
airway are either struggling for air (not
lying still) or they are very near death
from hypoxia (extreme urgency); both
of these situations can make the procedure difficult even for experienced physicians. In a combat setting, many patients with airway obstruction will have
penetrating trauma of the neck and/or
face with hemorrhage that extends into
the anterior neck, distorting the anatomy
(often the source of obstruction) and
presenting a risk of exsanguination if a
17
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
surgical airway is attempted. Proper
lighting, asepsis, and other environmental considerations are also frequently far less than ideal in a combat
setting.
immediate death. Army combat medics
in the 91W training program currently
(as of 22 June 2004) receive two hours
of lecture/discussion and twelve and
one-half hours of practical exercise on
all aspects of airway management; 30
minutes of this being dedicated to didactic teaching of a surgical airway and 4
hours spent on a practical exercise
teaching a standard cricothyroidotomy.
Previously this instruction had included
training on the use of the Cook Melker
percutaneous cricothyrotomy device51
but, because of the lack of a inexpensive
training device for the Melker airway
this was discontinued.
Current surgical airway management
training is limited by the use of plastic
models and cadavers which do not bleed
or struggle and die. New sophisticated
simulators can replicate physiology
[http://www.meti.com] and thus are a
significant improvement over simple
plastic models and some of the new
plastics are very lifelike and can even
simulate bleeding when cut. Animal
models such as large goats and pigs are
much better for training purposes but
they are expensive and the use of animals is becoming increasingly problematic. Interestingly, it is documented that
as long ago as 1000 AD, Ibn Zuhr is
reported to have successfully performed
a tracheotomy on a goat, so this animal
model for a surgical airway has a long
history [http://www.entlink.net/museum/
exhibits/Early-History.cfm?
renderforprint=1].
Large pigs are the best animal model for
surgical airway training because, of the
animals used for this type of training,
their anatomy is the closest to that of
humans. Goats, by comparison, have a
very long and superficial trachea that is
easily accessible with low risk of serious
hemorrhage. For this reason, it is deceptively easy to perform cricothyrotomy
on a goat; successful students gain a
false perception that the procedure is
easy to perform in a combat casualty.
The other problem with animal models
is that the animals are anesthetized when
the airway procedure is performed (not
struggling), their anatomy is not distorted, and they generally have no airway obstruction so there is no risk of
Arthur Viera receiving a surgical airway by Doc
Carrara at LZ X-Ray in Vietnam, in We Were
Soldiers Once - And Young, by Joe Galloway
and Hal Moore. Viera is obviously awake, alert,
and has survived for some period of time with
his penetrating neck wound.
Combat medics (91W) are now taught to
perform a standard emergency crichothyroidotomy with insertion of a small
endotracheal tube. [91W Lesson Plan
Airway Management C191W002 / Version 1 22 June 2004 - 300-91W10 1
Health Care Specialist Task 081-8334528 Perform a cricothyroidotomy]
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Sustainment skill training in cricothyrotomy skill training is a unit responsibility and units, for the most part, do not
have models or devices for providing
this training. The reality is as follows for
most medics who would perform a surgical airway procedure on a combat
casualty:
•
•
•
•
He or she will have never before
done the procedure on live tissue
(animal or human)
The last time he or she did the
procedure was on a plastic manikin, more than a year before, during a mandated (not unit) training
requirement
The procedure will be unsupervised by someone experienced in
the successful performance of the
procedure
The surgical environment will be
far from ideal.
All of these factors suggest that when a
combat medic performs a cricothyoidotomy on a casualty with an apparent
airway obstruction there is a reasonably
high probability that the procedure will
be done when not indicated and/or it
will be unsuccessful. In fact the procedure is most likely to be successfully
performed on casualties in whom it is
not indicated because they are less likely
to have grossly distorted anatomy, they
are probably not struggling, and there is
likely less urgency, so the procedure can
be performed in a more controlled manner. While it is certainly true that there
are some situations in which a surgical
airway would be indicated in a patient
without an immediately critical airway
obstruction, the ability of a combat
medic to discern this patient from one
who does not need this procedure is
probably not very good.
Airway
Risks
Unfortunately, it is quite possible that
although some patients could be saved
by establishment of a surgical airway,
almost as many may be killed or permanently harmed by the procedure itself.
Inexperienced medics in the field are not
only less likely to effectively manage an
airway using non-surgical methods but
they have a higher likelihood of complications and a lower likelihood of success when attempting to open an airway
surgically. If the adverse outcomes only
occurred in patients who truly had airway obstruction that couldn’t be relieved with less-invasive methods, there
would be no harm in attempting to establish a surgical airway (no matter how
unskilled the medic) because otherwise
these patients would surely die. Unfortunately, the less trained and less experienced the provider, the more likely it is
that a surgical airway will be attempted
when it is not indicated; which subjects
patients who do not stand to benefit
from the procedure to increased risk of
complications and death.
It is worth noting that the recipient of
the first recorded “successful” cricothyrotomy, performed in 1852, later died
from airway stenosis.52 Cricothyrotomy
is associated with a historically high rate
of difficult-to-manage subglottic stenosis and other complications that include
life-threatening hemorrhage, airway obstruction, bronchospasm, cuff leak, esophageal perforation, paratracheal insertion, aspiration, infection, pneumomediastinum, pneumothorax, subcutaneous
emphysema, or tracheoinnominate fistula.53 Given the rarity of combat trauma
patients sustaining airway obstruction
that requires surgical intervention, it is
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
probable that the number of times this
procedure would be done when not indicated is likely to greatly exceed the
number of times it would be done when
indicated; and some percentage of these
casualties will suffer procedureassociated complications.
the dead makes it unclear how
many attempted cricothyrotomies
were successful [Note: the authors
do suggest that the procedure was
not the cause of death stating
“Since the RTS and GCS were
significantly higher among the
survivors, it appears that the high
mortality rate in this series was injury-related” and was not related
to the procedure.54]
Success was not defined using any
objective measure such as confirmation of end-tidal CO2. (i.e., it
was determined subjectively by
the performer of the procedure,
was not independently verified,
and was defined as the establishment of an effective airway and
achievement of “reasonable” ventilation as determined by auscultation).
Although similar concerns exist about
the establishment of a surgical airway
when performed by a physician’s assistant or medical officer, these individuals
should have had more training and more
experience than the typical combat
medic. The Israeli experience, as reported in a 1997 study of physicianperformed pre-hospital cricothyrotomies, is that cricothyrotomy performed
in the field by physicians, even ones
inexperienced in the performance of
cricothyrotomy is successful in most
(89.6%) cases.54 In this study cricothyrotomies were done on only 3.3% of all
patients requiring pre-hospital airway
procedures; nearly two-thirds having
sustained penetrating trauma (Israel may
be somewhat unique among developed
countries because of its disproportionately high percentage of patients sustaining penetrating trauma). It is, however,
unclear how these cricothyrotomies
were deemed successful or unsuccessful.
Because there is no indication in this
study that autopsies were performed on
those who died, it is not possible to determine whether the cricothyrotomy was
an associated cause of death or even
whether the procedure had been performed properly
Statistical analysis notwithstanding, the
reported success rate in the above study
may well be inflated because:
•
•
Overall mortality was 55.1%
Lack of autopsy confirmation of
airway success or failure among
•
There is also reason to believe that some
of the patients reported in this series did
not actually need a surgical airway.
Three patients, despite having an unsuccessful cricothyrotomy and experiencing
associated complications, arrived at the
hospital alive, surviving both their “airway obstruction” and their unsuccessful
surgical airway attempt. These issues
aside, the authors note that following
brief training (e.g., the ATLS course)
physicians are apparently capable of
performing emergency cricothyrotomies
in the field and their success rate without complications appears to be unrelated to medical specialty.
Certainly in the context of the failed
airway, cricothyrotomy provides the
ultimate fallback airway management
technique and, as such, it should be in
the armamentarium of the forwarddeployed physician’s assistant and
medical officer.48
20
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Equipment - Non-surgical Airway
Management
Bag-Valve Mask
Although a bag-valve mask is an essential item of equipment for assisted ventilations, it is reasonable to question its
utility forward of a Battalion Aid Station. In a civilian setting respiratory arrest in patients with non-traumatic injury
is not uncommon and many such patients can be saved with ventilatory assistance. Further, respiratory arrest in
civilian trauma patients is generally due
to closed head injury; some of which
can be saved with ventilatory assistance.
In combat, however, trauma-associated
respiratory arrest is usually due to penetrating trauma, and very few patients
with such injuries can be saved even
with good ventilatory assistance. As is
true with advanced airway procedures
there are certainly some combatassociated circumstances for which ventilatory assistance may be life-saving in
the forward combat areas; these include,
but are not limited to:
•
•
•
•
•
Closed head injury
Electrical shock
Lightning injury
Chemical warfare (particularly
those involving the use of nerve
agents)
Drowning.
Bag-Valve Mask, from from United States Naval
Hospital Corpsman 3 & 2 Training Manual
NAVEDTRA 10669-C June 1989
Airway
Not only is the bag-valve mask unlikely
to favorably improve the outcome of
most combat casualties, but most providers find it difficult to use this device
effectively as a sole provider. The
American Heart Association in their
Advanced Cardiac Life Support Course
clearly state that, “a single rescuer may
have difficulty providing a leakproof
seal to the face while squeezing the bag
adequately and maintaining an open
airway.” For this reason, manually operated, self-inflating bag-valve-mask units
are used most effectively by at least two
well-trained and experienced rescuers
working together.”55 A smaller and
lighter item, which is can be much more
effectively used by a single person, is
the pocket mask. For the majority of farforward, point-of-wounding, circumstances the pocket mask is not only sufficient but is a superior choice.
Suction Devices
As indicated earlier, vomitus, blood,
and tissue are common causes of airway
obstruction in combat casualties. Most,
but not all, of these common causes of
obstruction can be cleared by proper
casualty positioning and digital clearing
of the airway. Various suctioning devices are available to aid in the clearing
of liquids and small particulate matter
from the airway. The ideal battlefield
suction device should be:
•
•
•
•
•
Lightweight
Compact
Durable
Effective
Hand operated.
Many of the suction devices used by
civilian EMS personnel are electrically
operated. In addition to requiring electrical power such devices are generally
21
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
too bulky and too heavy for use by
combat medics who must rely on handoperated devices.
An aspirator, called the SuctionEasyTM
disposable suction is now available that
meets several of the characteristics of an
ideal combat suction device. It is essentially a modified and enlarged infant
bulb aspirator with a reservoir that can
hold up to 1000 cc’s of aspirated material.
V-VAC™ Manual Suction Unit (Photo courtesy of
Laerdal Medical Corporation)
In a recent evaluation of several commonly used, commercially available,
hand-operated suction devices (along
with some prototype devices and a 60mL Toomey syringe) by 17 Special Operations Forces enlisted medical personnel, the modified Delee suction device
and the V-VAC™ Manual Suction Unit
(whose major drawback was its bulky,
non-compressible, size ) were preferred.56
As a field-expedient, small, simple,
readily-available suction device, the 60mL Toomey syringe, although less than
ideal because it does not come with an
aspirator tip, it has a narrow opening
and thus is not effective at removing
most thicker and particulate matter, and
because it has a limited capacity, seems
to be the best of the options currently
available because of its ease of use and
ready availability.
It is simple to use, has no moving parts,
is lightweight and reasonably compact,
has an aspirator tip as large as that on
most commercially available suction
devices for pre-hospital use, and is capable of generating a vacuum force of
approximately 100 mm Hg – more than
sufficient suction to clear blood and
vomit from an adult airway. This suction
device might also be used in lieu of an
esophageal detector device to confirm
endotracheal tube placement (see following discussion below) but it has not
been evaluated for this application nor
has it been tested against other suction
devices to determine its efficacy in the
hands of military pre-hospital personnel.
Airway Adjunct
Almost by definition, any patient who
can tolerate proper placement of an oropharyngeal airway needs to be intubated, and probably needs at least some
assisted ventilation. In conventional
combat the majority of casualties in
whom an oropharyngeal airway would
be indicated have severe neurological
injuries or are in severe shock. Survival
of such patients, even when properly
managed and under relatively ideal circumstances, is unlikely.
22
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
obturator and esophageal gastric tube
airways were single-lumen airways designed to obstruct the esophagus and
direct airflow into the trachea. These
devices were associated with an increased risk of death, frequently because
of unrecognized tracheal instead of esophageal obstruction; they have been described a prominent trauma surgeon,
Ken Mattox, as being “instruments of
the devil.”
Oropharyngeal Airway
Nasopharyngeal Airway
Some of the newer devices are doublelumen devices that can be inserted either
into the trachea or the esophagus and, if
the proper ventilation tube is selected,
allow for effective assisted ventilation
with a bag-valve mask. The CombitubeTM
[http://www.life-assist.com/combitube],
pharyngotracheal
lumen
airway
[http://www.gettig.com/ptl], and the laryngeal tube airway are examples of
devices that have a large-volume balloon that inflates in and seals the posterior pharynx and a distal balloon of
smaller volume that inflates in the trachea or, more often, in the esophagus.5860
For these reasons, in combat, oropharyngeal airways, even if properly
used, are unlikely to have much effect
on morbidity or mortality. An alternative airway adjunct is the nasopharyngeal airway. This airway can be used in
both responsive and unresponsive patients and, if used properly, can be
safely inserted in most patients with facial trauma.
Airway Device
There are currently available a number
of airway devices that do not require
direct visualization of the vocal cords
and are designed to be inserted blindly.57
Earlier devices such as the esophageal
With these devices it is critical to correctly identify which port to ventilate.61
After confirming the location (trachea or
esophagus) of the distal tip of the airway, which is best accomplished using
an end-tidal CO2 detector, ventilation is
provided through the proper port. In addition to helping secure a patent airway,
the upper, large-volume balloon on
these devices can potentially compress
and control bleeding in the upper airway
and thus, in some instances these devices may be the ideal airway device for
some patients with maxillofacial trauma.
The pharyngotracheal lumen airway was
evaluated for its ability to control simu-
23
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
lated upper airway hemorrhage and was
found to be effective.62
taught for advanced airway management.65
Another type of blind insertion device is
the laryngeal mask airway. When inserted this device creates a seal around
the upper portion of the airway in the
posterior pharynx thus directing air into
the trachea. All of these devices have
been tested both by anesthesiologists in
an operating room setting and by prehospital personnel in a field setting and
have been found to provide effective
ventilation comparable to endotracheal
intubation if used properly.63 In a study
of endotracheal tube, laryngeal mask
airway, and CombitubeTM use by Navy
Seal and Reconnaissance combat
corpsmen under simulated combat conditions, insertion time for the laryngeal
mask airway (22.3 seconds) was significantly shorter than the insertion times
for the other devices.64 The corpsmen
easily learned how to use the CombitubeTM and laryngeal mask airway, and
had a similar rate of attempts for all devices (1.17 to 1.25). The authors concluded the following:
Devices to Confirm Endotracheal
Intubation
Simple airway devices that allow for
easy learning, rapid insertion, and
minimal deterioration in skill over
time could significantly improve
corpsmen’s' ability to care for patients in combat conditions.
It should be noted that complete airway
protection is only provided in those instances in which a cuffed airway is
placed in the trachea. Some of these
blind insertion devices can easily be
converted by a physician to a cuffed
endotracheal tube in a controlled environment. Although generally safe and
easy to use, these devices are associated
with occasional complications. In 91W
training it is the CombitubeTM that is
Although endotracheal intubation is not
generally indicated for most combat
trauma patients (see above discussion),
if it is performed, it is absolutely essential that confirmation be obtained that
the trachea, and not the esophagus, has
been intubated. The former gold standard of observing the tube pass through
the vocal cords, confirmation of bilateral
breath sounds on ventilation, and absence of ventilation sounds over the
stomach is inadequate.66 The new prehospital gold standard is capnographic
confirmation of the excretion of carbon
dioxide, usually with a colorimetric
CO2 detector. Another commonly available, field-durable, and effective confirmation tool is the esophageal detector
device, or EDD. This is a bulb-suction
device that relies upon the fact that
when suction is applied to the end of the
endotracheal tube, the esophagus, but
not the trachea, will collapse. Confirmation of tracheal intubation is obtained
when the EDD is placed on the end of
the ET tube, compressed, and rapidly
refills when compression is released.
Either, or preferably both, of these confirmation tools should be used any time
endotracheal intubation is performed.66-
71
No single method is completely adequate to confirm proper tube placement
with 100% certainty so whenever possible multiple methods should be used
together to achieve the highest degree of
certainty possible. Unfortunately unrecognized esophageal intubation continues
to be an all-too-common cause of iatro-
24
Immediate Care of the Wounded
Clifford C. Cloonan, MD
genic mortality in the pre-hospital setting.
Equipment for Surgical Airway
Management
It is not the intent here to describe, in
detail, how to perform a surgical cricothyrotomy or to list each item needed to
establish a surgical airway; this information can be found in many other
places.72 The intent is to highlight critical steps, compare different methods
and equipment, and assess the efficacy
of these different techniques when applied by pre-hospital personnel.
Standard Surgical Airway
Equipment
The basic equipment required to establish a surgical airway using the standard
technique is limited and, largely for this
reason, the standard technique is often
preferred. Several of the required items,
such as a scalpel with a # 11 blade,
gauze, hemostats, needle holder, and
scissors are commonly found in
medic/corpsmen aid bags.
Other helpful items that are not generally carried include a tracheal dilator, a
tracheal hook, and a low-pressure cuffed
tracheotomy tube such as Protex or
Shiley (size 5 or 6, with an 8-mm or larger internal diameter).
Although a surgical airway can be established with just a knife and an appropriately sized, cut-down, endotracheal tube
(or less73), this procedure, which might
seem easy when performed on an anesthetized goat, can go disastrously wrong
when performed with improvised, inadequate, equipment under suboptimal
conditions. Proper performance of this
procedure is outlined well elsewhere.72
Airway
Establishing a surgical airway using
standard surgical technique and minimal
equipment can certainly be done by a
trained combat medic. Unfortunately,
the circumstance in which this standard
surgical approach is easiest to perform
in a combat setting is when the casualty
is not struggling and when there is
minimal to no bleeding -- conditions
most commonly found in casualties who
are already dead.
Cricothyrotomy.
Percutaneous Dilational
Cricothyrotomy
Although the Israelis53 and others74 have
found similar complication and success
rates between the standard surgical airway approach and the Seldinger technique (and found that the standard approach was faster) others have suggested
that a Seldinger or modified Seldinger
technique is faster, has lower complication rates and higher success rates.75, 76
A major problem with some of these
comparative studies is that the two different cricothyrotomy techniques have
been evaluated using cadavers, which
don’t bleed, move, or have distorted
airway anatomy.72, 75
Toye & Weinstein76 introduced the
technique of percutaneous tracheostomy
in 1969. The technique was subsequently modified by Ciaglia et al.77 in
1985 and has gained widespread acceptance among surgeons and intensivists.
The advantages of this technique include
a small skin incision, less soft-tissue
dissection, and wire-guided, controlled
placement of the airway into the trachea.
Advocates of percutaneous tracheostomy cite the ease and ability with
which non-surgical specialists can per-
25
Immediate Care of the Wounded
Clifford C. Cloonan, MD
form this technique outside the operating room.78
A number of percutaneous cricothyrotomy kits are marketed (such as the PertrachTM, Nu-TrachTM, Melker Emergency Cricothyrotomy Catheter Set, and
the RapitrachTM, to name a few). Each
of these devices utilize a similar concept, that is the insertion of a needle into
the trachea, through which a guidewire
is inserted (Seldinger technique) followed by dilation of the puncture site
with a wire-guided dilator to facilitate
placement of a functional airway.
The PertrachTM device combines the
guidewire and the dilator and uses a
unique, splittable needle that is divided
and removed once the combined
guidewire/dilator has been introduced –
this simplifies the insertion process and
reduces insertion time. Both an advantage and a disadvantage of the PertrachTM device is that it uses a cuffed
airway. While a cuffed airway is ideal
and reduces the risk of aspiration the
cuff increases the diameter of the tube
that must be inserted and thus makes
insertion more difficult – significant
insertion force is often required with this
device.
Advantages of all of these Seldingertype devices over standard surgical dissection include less bleeding, ease of
learning, and more rapid insertion. A
study by Toye & Weinstein in 1986 of
100 patients treated with an early version of the PertrachTM device revealed a
total complication rate of 14%, of which
6% was due to false passage of the device, or paratracheally rather than intratracheally.79
An unpublished in vivo evaluation of
four cricothyroidotomy devices carried
Airway
out at the Institute of Surgical Research,
Brooke Army Medical Center, Fort Sam
Houston found that of the devices available in 1990 (the Melker device was not
available at that time), the PertrachTM
was the most rapidly inserted by nonsurgically-trained practitioners into a
porcine model.80 Because each of the
available Seldinger-type surgical airway
devices includes some type of dilator to
create an opening in the cricothyroid
membrane, tissue dissection is minimized.
When a cuffed airway is to be inserted,
the opening through the skin and into
the trachea has to be larger than the dilator. Unless an incision is made that is
large enough to facilitate easy passage
of the cuffed airway, significant pressure will be required to insert the cuffed
airway.81
Use of lubrication on the airway can
help to reduce insertion forces. Special
Operations medics in training at the
Joint Special Operations Medical Training Center in Fort Bragg, North Carolina
informally assessed the PertrachTM and
Melker devices in terms of ease of use.
Their primary complaint about the PertrachTM was that significant force was
required to insert the cuffed airway.
They tended to prefer the Melker device
because it was easier to insert. The
Melker device has a significantly
smaller internal diameter than the PertrachTM and does not have a cuff.
Although a smaller uncuffed airway
may be an adequate rescue airway device it is inadequate for sustained use
(beyond more than a few hours) because
of the increased work of breathing and
because the lack of a cuff increases the
risk of aspiration. When a casualty arrives at a medical treatment facility with
26
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
a small, uncuffed, airway, the airway
will have to be replaced. Although this
is a disadvantage, an uncuffed airway
can certainly be replaced later with a
cuffed airway in the more controlled
setting of the medical treatment facility.
For this reason it might not be unreasonable to select from among the available
surgical airway devices and techniques
the one that is fastest, easiest, and least
risky for pre-hospital personnel to employ, even if it must later be replaced.
will require time-consuming operative
procedures…therefore surgery should be
attempted only under controlled conditions.”3
Previously the Army Medical Center
and School at Fort Sam Houston had
taught 91W combat medics to perform
percutaneous cricothyrotomy using the
Melker device but this has been discontinued because the lack of a costeffective training device limited effective training. Currently combat medics
are taught to perform a standard surgical
cricothryoidotomy with the insertion of
a small endotracheal tube.
During World War II it was determined,
based on experience, that casualties with
serious maxillofacial injuries were best
handled in evacuation hospitals, where
trained oral and maxillofacial surgeons
could be readily available to treat them.
It was felt that maxillofacial teams were
more usefully employed in the rear areas
at evacuation hospitals rather than in
field hospitals. It was found that if hemorrhage could be controlled and a proper
airway established and maintained that
casualties with maxillofacial trauma
could tolerate transportation very well if
kept in a prone (not supine), or sitting up
and leaning forward, position. It was,
however, noted that such casualties may
require the attention of special attendants during evacuation.82
Evacuation of Casualties with
Maxillofacial Injuries
In World War II it was found that with
proper forward area medical care casualties with maxillo-facial wounds could
receive delayed definitive medical care
without adverse consequence. The history of the activities of the 2nd Surgical
Group states that, “In the average maxillo-facial case immediate surgery is not
imperative and in the presence of
haemostasis, clear airway, and a reasonably comfortable patient, it is wise
first to reduce shock to a minimum.”3
This history also reveals that “The mean
average time from [facial soft tissue]
injury to first definitive treatment was
eight hours” and, “The mean average
time from injury to arrival at the Center
[2nd Auxiliary Surgical Group] was four
days.” It was noted that, “Many cases
27
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
SUMMARY
Although having a patent airway is critical to survival, advanced airway management of combat casualties by medical specialists is rarely required. Penetrating trauma, the predominant form of
trauma on the battlefield, infrequently
produces airway obstruction and when it
does, the obstruction is usually immediate, causing death before treatment by a
medical specialist is available. Further,
the majority of treatable airway obstruction that occurs in combat casualties can
be managed by basic airway maneuvers
that include proper positioning, suctioning, digital removal of debris from the
airway, head tilt/jaw thrust, and insertion of a nasopharyngeal airway.
Advanced airway management, specifically intubation and cricothyrotomy, is
very rarely required for combat casualties. At, or near, the point of wounding
there is a high probability that these
rarely performed procedures will be
done incorrectly, when not indicated, or
both – especially when performed by
personnel with minimal training and
inexperience with the techniques. All of
this leads to a reasonable conclusion that
the emphasis of airway management
training for soldiers and medics needs to
be on well-executed basic airway clearing maneuvers using either no airway
adjuncts or simple, durable, lightweight,
and uncomplicated equipment; perhaps
the most important of these being effective suction. In addition to hemorrhage
control, all soldiers should be taught
proper casualty positioning and basic
airway clearing techniques. Realistic
simulators capable of recreating the
types of airway obstruction likely to be
found in battlefield casualties and able
to be utilized in realistic combat scenarios are essential for effectively training
pre-hospital personnel. Training therefore, and not equipment, should be the
primary focus of efforts to improve the
survival of combat casualties with airway obstruction. If military pre-hospital
personnel are to be taught to perform
advanced airway procedures such as
endotracheal intubation, rapid sequence
intubation, and/or cricothyrotomy, it is
essential that they be properly trained,
sustained, and evaluated to ensure competency. They must also be equipped
with, and trained in the use of, airway
rescue devices that are easy and safe to
use and there must be some mechanism
of oversight put into place to ensure that
these procedures are being done properly and only when indicated. Further, it
is important to conduct studies to determine whether overall survival of combat
casualties is actually increased through
the use of these procedures by prehospital personnel.
28
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Airway
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Airway
80.
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Copyright 2007
The Brookside Associates, Ltd.
All Rights Reserved
34
Immediate Care of the Wounded
Clifford C. Cloonan, MD, FACEP
COL (ret) U.S. Army
Associate Professor
Department of Military & Emergency Medicine
Uniformed Services University of the Health Sciences
Breathing
Breath is the bridge which connects life to consciousness, which unites your body to your
thoughts.
Thich Nhat Hanh
Courage is a matter of the red corpuscle. It is oxygen that makes every attack; without
oxygen in his blood to back him, a man attacks nothing-- not even a pie…
Elbert Hubbard
“Wounds of the chest, when taken as a class, are perhaps the most fatal of gunshot
wounds”1 (p.276)
Julian J. Chisolm, Confederate Surgeon
1
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
the chest for long periods and attempts at
removal may convert a relatively minor
wound into a more serious penetrating
wound.3 In his monograph Fraser3 tells the
tale of a wounded soldier, who after tolerating being “poked at” for a long time by a
surgeon finally inquired as to the point of
the procedure. The surgeon said that he
was searching for the bullet, to which the
wounded man reportedly replied, “I wish
you had said so earlier, because you will
find it in my waistcoat pocket.”
History and Epidemiology of
Thoracic Injury and Respiratory
Impairment in Combat Casualties
History
Throughout most of the history of warfare
injuries of the chest, particularly penetrating injuries, have had a dismal outcome
even for those surviving long enough to
receive some form of medical attention. In
1761 John Hunter, an Army surgeon,
noted that “usually little of value is done
for those with chest wounds” but despite
this he felt that, “something probably
could be accomplished for the good of the
patient.” His only contribution was to
suggest that hemothoraces might be
treated by allowing the fluid to run out of
the wound.2
Epidemiology
The great majority of casualties, in most
forms of combat throughout most of modern history, have sustained their wounds
as the result of unaimed, usually indirect,
fire. For this reason, differences in the location of wounds that might be related to
the type of weapon used should result only
from chance depending upon the mix of
weapons and rate of fire, and on the relative frequency and extent of exposure of
the various parts of the body. If these were
the only factors influencing wound distribution the overall prevalence of thoracic
trauma should then approximate the fraction of the body surface area that overlies
the thorax, or about 16% (depending on
how the thorax is defined). However, a
significant portion of casualties with thoracic trauma are killed outright so the actual percentage of the casualty population
requiring treatment for thoracic trauma is
smaller, somewhere between 5% and
10%.4[attributed to Beebe and DeBakey5
(p.181)
]
During the Napoleonic Wars Baron Dominique Larrey observed that patients sustaining penetrating chest trauma in which
the thoracic opening was larger than the
glottis had significantly worse outcomes
than those with smaller wounds. He, like
John Hunter, recommended that casualties
with penetrating chest wounds be placed
with the injured side down to permit blood
to drain out of the chest cavity but he went
further to suggest that the wound in the
chest should be closed.2
In his 1859 monograph on wounds of the
chest in the Crimean War3 Patrick Fraser
recommended “paracentesis thoracis”
without delay for chest injuries in which
blood or serum accumulated without the
ability to drain from an open wound in the
chest and thus impeded the lungs. Fraser
also noted that in most instances there was
more danger associated with attempts to
remove foreign bodies from the chest than
there was to simply permit them to remain
in situ; bullets may remain innocuous in
Differences in distribution and lethality
do, however, exist among various weapons types, especially in relation to fatal
wounds among the body regions hit. In the
Korean War lethality among all those hit
(killed and wounded, excluding cardedfor-record-only) was highest for bullets
2
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
low percentages are likely the result of not
including most of those killed outright on
the battlefield. During this war the overall
case fatality rate for chest wounds was
27.8 percent and was 62.6 percent for
penetrating chest wounds.2(p.5)
striking every region of the body except
the upper and lower extremities. Perhaps
not surprisingly this means that when
small arms are commonly used (usually in
close combat), the lethality of chest
wounds rises because high velocity bullets
tend to be lethal; especially when vital
areas are hit.6(p.44)
Of patients with chest wounds surviving
long enough to be seen in a base hospital
during the World War I, 70 percent had
chest wounds caused by rifle or machinegun bullets, 15 percent by bomb splinter,
and 15 percent by shrapnel. At the front
the incidence was almost the reverse with
40 percent of wounds being produced by
bullets and 60 percent by other projectiles.7(p.154)
As discussed in detail later, comparison of
the incidence of thoracic injury in various
different wars is hindered by the general
lack of a clear definition of what constitutes a thoracic injury. Furthermore there
are differences in incidence due to some
portion of casualties never being recorded.
For example, during the Crimean War,
only 3.9 percent of wounds were recorded
as involving the chest, 28.5 percent of
these being fatal. In this same conflict
chest wounds involving the lungs are recorded as only comprising 1.35% of all
wounds; 79.26 percent of these being fatal.
During World War I thoracic wounds accounted for only 2.6% of all hospital admissions and 8.2% of all hospital deaths.
At 28.85%, the case fatality rate for
wounds of the thorax during WWI remained quite high. It ranked as the third
highest cause of hospital associated death
behind wounds of the spine (55.85%) and
wounds of the abdomen and pelvis
(43.32%).8 Berry, in his chapter “Historical Note” in volume one of Thoracic Surgery in The United States Army – Surgery
in World War II series, notes that the reported incidence of thoracic wounds during WWI is suspect because the numbers
are entirely at variance with the incidence
reported in other recorded wars (far too
low).
Berry, in his historical section of the Thoracic Surgery volume of the Army Medical Department in World War II, noted
that these numbers are considerably lower
than predicted based upon body surface
area (roughly 9% for the anterior chest
and 9% for the upper back). He felt, therefore, that it is likely that during this war
the majority of casualties sustaining
wounds to the chest died on the battlefield,
never making it into the medical system to
have their wound recorded. Thoracic
wounds, most especially in conflicts before World War II, tended to be highly
lethal. The case fatality rate for wounds of
the lung in the French Army during the
Crimean war was reported to be 91.6 percent.3
This low incidence may be because some
wounds to the thorax were included with
wounds of the neck and back, for which
separate categories existed. A WWI German survey of causes of battlefield deaths
conducted by Sauerbruch and discussed
by Frank Berry in his chapter “General
Considerations of Thoracic Wounds”9 (p.64)
found that 30 percent of 300 battlefield
deaths had wounds of the chest. A similar
British survey conducted by Loeffler,10
During the Civil War only 8.1 percent of
wounds involved the chest; 42.3 percent
of these being penetrating. Again these
3
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
that was also cited by Berry,9(p.64) found
that of 469 WWI battlefield deaths 29 percent had chest injuries.
1) Presence of a sucking chest
wound
2) A large retained foreign body
3) Severe bony injury
4) Injury to the diaphragm and/or
5) “Extensive” hemorrhage.2(p.8)
Jolly noted that during the Spanish Civil
War the incidence of chest wounds varied
with the type of warfare. The incidence
tended to rise during war of movement
and fall with positional or siege warfare,
during which the thorax is naturally much
less exposed. He found that these factors
appeared to have a bearing on prognosis
as well because in open warfare the percentage of bullet wounds, most of which
are caused by the projectile entering at
right angles, is high while in trench warfare there is a relatively high incidence of
tangential wounds of the chest wall and of
wounds caused by flying fragments. The
prognosis for the former was far better
than for the latter.7(p. 150)
The case fatality rate for chest wounds
significantly improved in World War II, as
compared to World War I, but sadly the
treatment of chest wounds at the beginning of WWII, immediately following
Dunkirk, left much to be desired. Almost
all casualties who received surgery for the
chest wound they sustained at Dunkirk
had wound repair without wound excision
and no provision was made for drainage of
the chest. This resulted in a large number
of infections.
In his section of the series, “The Army
Medical Department in World War II”
Berry noted that, “Ironically a number of
the casualties regarded as being too severely wounded to withstand surgery may
have owed their lives to the fact that their
wounds were not sutured closed and only
a simple field dressing was applied.2(p.32)
By the end of the war the cumulative case
fatality rate for chest wounds had fallen
significantly to 5.4%.2(p.7)
Jolly also noted the effect that early mortality has on the frequency of certain thoracic injuries seen at medical treatment
facilities, saying that, “Haemothorax as
the result of wounds of the heart, the great
vessels or the hilum of the lung is also
very rare, for such cases usually succumb
immediately.7(p.150)
In World War II casualties with wounds of
the thorax accounted for 7.24 percent of
all hospitalized wounded and 8.3 percent
of all who died once hospitalized
[DOW].9(p.61) Thoracic wounded casualties
accounted for 9.3 percent of all KIA in
World War II and thoracoabdominal
wounds accounted for 0.16 percent.9(p.69)
During the Korean War the thorax was
listed as the site of wounding in 7%6(p. 46)
of all casualties and the overall fatality
rate for wounds of the thorax was
27%.6(Table 46 p.44) Penetrating trauma was
the most common cause of death in Korean War casualties with chest wounds,
accounting for 41.2% of all mechanisms
of death in thoracic wounded casualties.
Rib fracture(s) caused 6.3% of thoracic
wound deaths and 10.9% of this category
died from concussion (blast).6(Table 48 p.45)
Not surprising the fatality rate for bullet
wounds of the chest, at 34.7 percent, was
much higher than the overall rate.6(Table 46
First aid of chest injured casualties during
WWI was limited to control of bleeding at
the site of the wound combined with temporary wound closure by a thick dressing
taped firmly over the wound.2(p.8) In World
War I the indications for immediate thoracotomy were:
p.44)
4
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
The overall case fatality rate for all
wounds during the Korean War reached a
new low of 2.5%; significantly lower than
the 4.5% rate of WWII. Not surprisingly
the case fatality rate for thoracic wounded
casualties remained considerably higher
than the overall rate. The average case
fatality rate for thoracic wounded casualties during the Korean War was 5.3%6(Table
49 p.45)
with wounds of the thorax accounting for 21% of all casualties dying of
wounds.6(Table 45 p.43) The case fatality rate
for chest wounded casualties varied considerably between the various wounding
mechanisms/agents.
In a recent review of the Vietnam War era
WDMET files [McPherson J, Feigin DS,
and Bellamy RF: Prevalence of Tension
Pneumothorax in Fatally Wounded Combat Casualties. DRAFT pending publication], Bellamy and colleagues found that
663 of 893 deceased combat casualties
(74%) with readable post-mortem radiographs had radiographic and/or clinical
evidence of a chest injury. In 9% (80) the
fatal injury had occurred in the thorax. In
the remainder there was fatal injury in another part of the body, usually the brain. In
this WDMET review autopsy reports
showed that the fatal chest injury involved
the heart and/or great vessels in 2.8%
(25/893) of cases. The actual number of
fatal heart or great vessel wounds in this
series was almost certainly greater than
estimated since radiographs of such casualties, which is what was reviewed in this
study, did not necessarily show evidence
of mediastinal displacement or even
hemothorax.
When the chest wound was caused by a
bullet the case fatality rate was 7.2%,
when caused by a fragment it was 4.9%,
and it was 5.3 percent when caused by a
land mine.6 Because the great majority of
those with serious pulmonary, major thoracic vascular, or cardiac wounds die before any medical care can be provided and
because the majority of those surviving
initial wounding who do require a surgery
only need a chest tube; the number of
casualties requiring thoracic surgery in an
operating room is quite small. During the
Korean war thoracic surgery only accounted for 1.3% of all surgical operations
in an operating room and operations for
wounds of the heart, pericardium, and
great vessels accounted for less than 0.1%
of all surgeries.6(p. 86)
As noted in the Textbook of Military
Medicine4(p.457) 12% of 7,500 total casualties seen at the 24th Evacuation Hospital
during the Vietnam War had injuries involving the chest; 61% of these having
had an intrathoracic injury. The cause of
the intrathoracic injuries was fragments in
443 (81%), bullets in 76 (14%), and blunt
injury in 28 (5%). No intrathoracic injuries were attributed to blast in this series.11
Casualties with thoracic injuries commonly have other injuries as well. Eightyfive percent of casualties seen at the 24th
Evacuation Hospital in Vietnam,11 and
eighty percent of chest wounded casualties
seen at the Rambam Medical Center in
Haifa, Israel12 had one or more additional
injuries involving another part of the
body.
In Reister’s Korean War data on anatomic
wound location, no significant variation or
major shift is apparent between body regions in the relative distributions, either
by type of operation or for different periods of time during the war. Because there
was no statistically significant shift of
wounds from thorax and abdomen to some
other body region after body armor was
introduced on a limited basis it is not possible to draw any conclusions from this
data as to the efficacy of body armor.6(p.51)
Most data from wars occurring within the
past 35 years, with the exception of the
findings of one surgeon in Lebanon,13, 14
5
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
point of the 11th rib and the spine of
the first lumbar vertebra. The chest
region as described includes that entire circumference of the trunk and is
not interrupted posteriorly by a
“back” or a “spine”.
indicate that a formal thoracotomy is
needed in only about 10% to 20% of casualties with thoracic injuries who survive to
reach a military hospital.4(p.458)
Epidemiology of Civilian Thoracic
Trauma
Civilian epidemiology of chest trauma,
like that of the military, is complicated by
the fact that significant underreporting of
thoracic injury can result when data is
only gathered on those surviving long
enough reach hospital level care. Thoracic
injury, particularly penetrating thoracic
injury and blunt injury involving the heart
and great vessels, has a high pre-hospital
mortality. Thoracic great vessel injury
accounts for approximately 8% to 9% of
vascular injuries, most of these being
caused by penetrating mechanisms.15
Before discussing the epidemiology of
thoracic trauma, whether it be civilian or
military, it is essential to have a standard
definition of what body area actually constitutes “the thorax.” Unfortunately the
epidemiology of thoracic trauma is often
reported without there being included a
precise definition of what constitutes a
thoracic wound. This has led to confusion
when comparisons are made both between
civilian trauma and military trauma, and
between the rates of thoracic trauma in
various military conflicts.
Blunt disruption of the thoracic aorta is
usually rapidly fatal prior to hospital arrival; it is estimated that only 10% to 20%
of patients with these injuries survive to
reach an emergency department (ED).16, 17
Thus, if rates of thoracic trauma are based
only upon it’s frequency in patients who
survive to be seen in a hospital, there will
be significant under-reporting.
Berry in the “Thoracic Surgery” volume
of the Army Medical Department in
World War II series9(p.59) stated that, “It is
regrettable that up to this time there has
been no agreement as to exactly what portion of the body constitutes the chest.
Without a generally accepted definition,
there has naturally been disagreement in
the statistics for chest wounds.” Following
the Korean War, Beebe and DeBakey, in
their book, “Battle Casualties”5 (p.89) recommend the use of Churchill’s definition
of the chest. Churchill defined the chest as
being:
Injuries of the chest wall and lungs are
common. Chest trauma has been estimated
to cause 20% of all civilian traumatic
deaths regardless of mechanism. This has
been calculated to be about 16,000 deaths
per year in the United States.18 A cooperative study from 60 hospitals showed that
among victims sustaining thoracic trauma,
50% will have chest wall injury; 10% being minor, 35% major, and the remaining
5% having flail chest injuries; injuries to
the lung parenchyma are reported to occur
in 26% of patients.18 According to
LoCicero and Mattox in 1989 chest
trauma was the second most common
cause of traumatic death in the United
“…On the surface…the simplest line
is one that approximately follows the
lower limits of the pleural cavities. In
front, this line passes from the lower
end of the sternum obliquely downward along the costal margin to the
8th intercostal space. A horizontal line
carried around the body to meet the
corresponding point on the other side
will pass approximately over the mid-
6
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
only estimated. The depth of respiration,
which is also important, is similarly rarely
assessed.
States after head trauma, accounting for
approximately 20% of deaths.18
In one study described by Orlinsky et al.19
pulmonary complications were noted in
approximately 10% of more than 3000
trauma victims. The lung is the most frequent organ involved in multiorgan failure
and is usually the first organ to fail after
injury.20 Respiratory failure has the highest mortality rate compared with failure of
other organ systems.19 Jones et al. found
that in traumatic chest injury, overall mortality is greater in blunt (40%) versus
penetrating (20%) injuries.21
Oxygenation involves the saturation of
hemoglobin with oxygen. Theoretically
this does not require ventilation although
practically it does because without ventilation oxygen cannot reach the alveoli. So
long as there is a high enough partial pressure of oxygen in the lungs, and there is
adequate blood flow, oxygen will move
from the lungs to the peripheral tissues.
Hypoxia resulting in anaerobic metabolism exists whenever the partial pressure
of oxygen available at the cellular level is
decreased (< 30 mm Hg). This can be due
either to a low environmental partial pressure of oxygen, or due to other problems
such as decreased delivery of oxygen
(anemia, hemoglobinopathies, and hypotension), increased utilization of oxygen, or inability to use delivered oxygen.
Physiology and Pathophysiology of
Ventilation, Oxygenation, and
Respiration in Combat Casualties
The focus of the following discussion is
on breathing-related basic physiology and
pathophysiology and on specific injuries
of the chest and lungs for which there is a
recommended pre-hospital treatment.
Ventilation, oxygenation, and respiration
are all covered. Each of these is a different
but related process. The first involves the
exchange of air between the lungs and the
atmosphere, and consists of pulmonary
ventilation (the total exchange of gasses
between the lungs and the atmosphere)
and alveolar ventilation (the effective ventilation of the alveoli, in which gas exchange with the blood takes place). Adequacy of ventilation is determined by assessing arterial pCO2; the measurement of
end-tidal CO2 is now possible in the prehospital environment.22 In general, however, in the pre-hospital environment assessment of ventilation is generally made
by determining respiratory rate and depth.
Unfortunately the importance of respiratory rate is generally underappreciated by
pre-hospital personnel and it is frequently
The causes of hypoxia have classically
been divided into four types:23
1)
2)
3)
4)
Hypoxemic
Anemic
Stagnant
Histiocytic24, 25
Histiocytic hypoxia refers to any condition
in which oxygen is available but cannot be
used by cellular mitochondria. This occurs
in circumstances such as poisoning with
cyanide and hydrogen sulfide.
In combat casualties all four of these types
each of these types of hypoxia can occur
singly or in combination. All types of hypoxia are discussed within this chapter but
only hypoxemic (anoxic) and histiocytic
hypoxia are discussed in this section;
anemic and stagnant hypoxia are discussed in the “Circulation” section.
7
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
resulting in hypoxemic hypoxia. This
might occur in conditions such as the adult
respiratory distress syndrome (ARDS) in
which there is increased interstitial fluid
surrounding the alveoli. Each of these
causes of hypoxemic hypoxia, except increased shunt (perfusion without ventilation), is corrected by supplemental oxygen23 so the response to supplemental
oxygen can be used differentiate shuntcaused hypoxia from these other causes.
Hypoxemic hypoxia has four main causes
and one much less common cause:
1)
2)
3)
4)
5)
Low partial pressure of oxygen
Hypoventilation
Shunting defects
Perfusion defects and rarely
Increased oxygen transit time
through the alveoli
The most easily understood is a low partial pressure of oxygen in the atmosphere
such as occurs at high altitude or when
there are other gasses, such as carbon dioxide, present in high concentration that
displace oxygen [Dalton’s Law of Partial
Pressures]. Hypoventilation is one situation in which carbon dioxide can accumulate inside the alveoli and displace oxygen
but, in general, the primary problem in
hypoventilation is hypercarbia, not hypoxia.
Respiration is the exchange of oxygen
between the atmosphere and the cells of
the body. This process includes:
1) Ventilation
2) Diffusion of oxygen from alveoli
to the blood and carbon dioxide
from the blood to the alveoli
3) Transport of oxygen to, and carbon dioxide from, the cells.
When some alveoli are perfused but inadequately ventilated (shunt) oxygenated
blood that has passed these alveoli mixes
with properly oxygenated blood producing
hypoxemic hypoxia. If there are large
areas of lung that are ventilated but not
perfused , e.g. a large pulmonary embolus,
these alveoli contribute to dead space in
which the exchange of oxygen for carbon
dioxide does not occur. This can cause
hypoxemic hypoxia because the CO2 content in this dead space is higher than inhaled air and this CO2 displaces some of
the inhaled oxygen leading to a lower alveolar PO2; however this is not the primary
reason for hypoxia in patients with pulmonary emboli as is discussed in detail
later.
The last of these processes involves blood
flow and problems in this area will be discussed in the “Circulation” section.
Combat trauma victims can experience
difficulties in one or more of each of the
above areas. Ventilation, the mechanical
movement of air in and out of the chest,
requires a functioning
1) Neurologic system to both generate the signal to breathe and to
transmit that signal to the endorgans of ventilation
2) Bellows to move air in and out of
the chest (intact diaphragm and
chest wall).
Traumatic injury to the brain, the upper
spinal column, or to peripheral nerves involved in the ventilation process can each
disrupt normal ventilation. Injuries that
disrupt the ability of the chest to generate
negative intrathoracic pressure also impair
ventilation. These include:
Finally it is at least theoretically possible
that in some rare cases there can be such
an increase in the distance across which
intra-alveolar oxygen must diffuse to
reach the passing blood that the hemoglobin in this blood remains unoxygenated
8
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
of Afghanistan) and when other gasses are
present in substantial quantity (Dalton’s
Law of partial pressures) that displace
oxygen; a situation that can occur when
carbon dioxide is produced by combustion
(explosion) in an enclosed space (e.g.
cave, vehicle, etc…).
1) Blunt and penetrating trauma to
the chest wall (flail chest, opening
of the pleural space to the atmosphere, etc.)
2) Direct injury to the diaphragm or
injuries that interfere with the
proper functioning of the diaphragm, and injury to accessory
muscles of respiration
3) Disruption of airflow in and out of
the alveoli from injury to the trachea and/or bronchus.
4) Finally ventilation can also be disrupted by severe pain on breathing
and by anything that restricts of
movement of chest wall and/or
diaphragm (circumferential burns
etc.).
In both of these combat situations supplemental oxygen would benefit combat
casualties until they could be moved to an
area with a higher partial pressure of oxygen. Once in an environment with a normal partial pressure of oxygen there would
be no continued benefit from oxygen.
Although it is indisputable that supplemental oxygen will raise the intravascular
oxygen content when hypoxia is due to
one of these causes, there have been no
military or even civilian, pre-hospital studies that have proven that supplemental
oxygen improves survival for trauma victims. A recent study by Stockinger and
McSwain26 addressed the issue of the efficacy of pre-hospital supplemental oxygen
in civilian trauma patients. They concluded that pre-hospital supplemental
oxygen provides “no survival benefit” for
trauma victims not requiring intubation
and ventilation.
Adequate cellular oxygenation is dependent upon there being a sufficient partial
pressure of oxygen in the alveoli, rapid
transfer of oxygen from the alveoli into
the blood stream, sufficient functional
hemoglobin to carry the oxygen, and a
properly working cardiovascular system to
transport oxy-hemoglobin out of the lungs
to the cells. The physiologic goal is to deliver sufficient oxygen to cellular mitochondria to allow aerobic metabolism. If
this does not occur, for whatever reason,
the cells will begin anaerobic metabolism,
and will eventually die. The body normally keeps the mixed venous pO2 around
40 mm Hg. If it falls below 30 mm Hg this
indicates that anaerobic metabolism is occurring in some circulatory beds.
The primary cause of inadequate cellular
oxygenation in battlefield casualties is an
inadequate quantity of hemoglobin due to
blood loss; and this cause of cellular hypoxia is only very marginally improved by
supplemental oxygen. The solution to this
cause of cellular hypoxia is to stop further
blood loss and, when indicated, to replace
blood loss with blood or another effective
oxygen-carrying solution (see discussion
in “Circulation” section).
Although uncommon, impairment of oxygenation in combat trauma patients can be
due to a lowered partial pressure of oxygen in the atmosphere. This would generally only be of clinical relevance when the
partial pressure of oxygen in blood drops
below 60 mmHg (roughly corresponding
to 90% saturation). Partial pressures this
low occur at very high altitudes (e.g. much
There are combat-related circumstances in
which supplemental oxygen may benefit
casualties in the pre-hospital environment.
Any situation that creates ventilation-
9
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Oxygen generators and compressed oxygen are both heavy, compressed gasses in
general are dangerous, and oxygen is particularly hazardous in a potentially flammable/explosive environment, e.g. combat. The higher the percentage of casualties suffering from conditions likely to
benefit from oxygen (high altitude or other
causes of hypoxia resulting from a lowered partial pressure of oxygen) the more
the equation shifts in the direction of
overall benefit.
perfusion mismatch (alveoli that are perfused but un- (or under-) ventilated) will
lead to some degree of cellular hypoxia
that will be improved with supplemental
oxygen. Types of combat casualties, who
might have some degree of ventilationperfusion mismatch and would therefore
benefit from supplementary oxygen include patients with blast lung, pulmonary
contusion, non-cardiogenic pulmonary
edema, drowning, nerve agent poisoning,
chemical pneumonitis (all causes including mustard agent), pulmonary anthrax or
other causes of pneumonia, and the adult
respiratory distress syndrome (shock
lung), to name a few. Oxygen is an important element in the resuscitation of all such
casualties but the incidence of such casualties on most battlefields is low.
High Altitude (environmental)
Hhypoxia
Although combat casualties rarely experience hypoxia as the result of a low environmental pressure of oxygen this has
happened during current operations in Afghanistan where almost 50 percent of the
total land area is above 2,000 meters in
elevation. Many of the strategically significant mountain passes in Afghanistan
lie at, or above 2,000 meters. At 4,420.7
meters, Mount Whitney, the highest
mountain in the continental U.S., is lower
than some of Afghanistan’s important
mountain passes and not much higher than
most of the others.27, 28
Asthma has increased in frequency in the
general population and with a recent relaxation of standards that will now allow
some volunteers with a history of asthma
to join the military there are an increasing
number of soldiers on active duty with
reactive airway disease. There are a wide
variety of triggers in a combat environment that might induce bronchospasm in
susceptible individuals; when severe bronchospasm occurs in such people supplemental oxygen and bronchodilators may
be life-saving.
It has been found during on-going operations in Afghanistan that almost all troops
deploying to combat operations above
8,000 feet (2,700 meters) experience some
degree of altitude related illness [10th
Mountain notes from Afghanistan
[http://pvtpyle.com/10th_mountain_notes_
from_afghani.htm – last accessed on 29
Jan 04] – and this in otherwise healthy
combatants. Altitude-related hypoxia in
combat casualties, particularly when it
compounds other causes of hypoxia, can
be the difference between life and death.
At sea level the inspired partial pressure of
oxygen is 150 mm Hg; at 2,000 meters it
drops to roughly 110 mm Hg; to 80 mm
A decision regarding whether to make
supplemental oxygen available in the forward battle areas, near the point of wounding, should be based upon a risk-benefit
analysis that takes into consideration the
probable incidence of conditions likely to
benefit from the availability of oxygen.
Since the cause of cellular hypoxia in
most conventional combat casualties is
acute blood loss, which is little benefited
by supplemental oxygen, in most combat
situations the “costs” probably outweigh
the benefits.
10
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
problem of hypercarbia. The real solution
to hypoventilation is not supplemental
oxygen, it is improved ventilation.
Hg at 4,000 meters; and at 6,000 meters to
less than 70 mm Hg.
Altitude-related hypoxia is exacerbated by
the fact that the decrease in intra-alveolar
oxygen pressure that occurs with increases
in altitude is nonlinear – as altitude increases the intra-alveolar oxygen content
drops even faster (especially at very high
elevations). This is because within the alveoli, at normal body temperature, the
partial pressure of water remains constant
at 47 mm Hg irrespective of the partial
pressure of other gasses. As a result during
ascent the partial pressure of water becomes an increasingly greater portion of
the total alveolar gas and displaces relatively more of the already lowered oxygen
content in the alveoli.
Ventilation – Perfusion (V/Q)
Mismatch
When it comes to oxygenation of hemoglobin ideally each of the pulmonary alveoli would be perfused so all would be involved in the exchange of oxygen and
carbon dioxide. In reality, however, some
alveoli are ventilated but not perfused
(dead space) and some are perfused but
not ventilated (V-Q mismatch/shunt).
Matching alveolar ventilation (VA) with
perfusion (Q) is a complex process, involving ventilation volume, alveolar pressure, compliance of lung and chest wall,
resistance of airways, gravity, position of
patient, pulmonary blood flow, and mode
of ventilation.
Hypoventilation
Hypoventilation is defined as a minute
ventilation (respiratory rate × tidal volume) that is inadequate to remove the carbon dioxide that is produced ( CO2 ).
When alveolar ventilation is inadequate, a
not uncommon occurrence in combat
casualties, carbon dioxide increases in the
blood and alveolus. As carbon dioxide
increases in the alveolus, there is correspondingly less room remaining for oxygen, so hypoxia occurs. Thus, the two
main physiologic features of hypoventilation are an elevation in the partial pressure
of CO2 in arterial blood and improvement
in arterial oxygenation (PaO2 ) with even a
slight a increase in the inhaled oxygen
concentration (FIO2 ).23 One cause of inadequate ventilation in combat casualties
is partial or complete airway obstruction.
When ventilation and perfusion are
matched, VA/Q = 1.0. Atelectasis, pneumonia, and pulmonary edema (low VA/Q)
all contribute to an increase in baseline
shunting (unventilated but perfused alveoli) and pulmonary emboli (high VA/Q)
cause an increase in the amount of dead
space (ventilated but not perfused alveoli).
Shunt, in which there is mixing of oxygenated and unoxygenated blood as the
pulmonary arteries bring blood back to the
heart, is the only mechanism of hypoxemia in which the PaO2 stays well below
the alveolar oxygen concentration even if
100% oxygen is being delivered to the
alveoli. This fact can be used to make a
diagnosis of shunting in a hypoxemic patient; if hypoxia does not improve with
administration of supplemental oxygen,
shunting (V/Q mismatch) is likely the
cause.
Hypoventilation can also be caused by
neurologic injury or chest trauma that either impairs ventilation or causes significant pain on breathing. Supplemental oxygen improves the hypoxia caused by
hypoventilation but does not address the
11
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
it is difficult to achieve and sustain a lethal
concentration, cyanide can be effectively
used inside enclosed areas. If used, cyanide acts by disrupting the utilization of
oxygen at the cellular level and in this way
causes cellular hypoxia.
Anemic Hypoxia
Anemic hypoxia occurs when there is insufficient functional hemoglobin to carry
the oxygen needed to meet cellular metabolic requirements. This is a common
cause of hypoxemic hypoxia in combat
casualties; the most common etiology being traumatic loss of hemoglobin. This
cause of hypoxemic hypoxia is discussed
in detail in the “Circulation” section of
this monograph.
Perhaps the most common, although still
rare, way in which combat casualties can
experience histiocytic hypoxia is carbon
monoxide poisoning. Most commonly this
occurs not as the result of enemy action
but from accidental causes such as when
troops burn fuels inside poorly ventilated,
enclosed spaces. The incomplete combustion of carbon fuels leads to the creation of
carbon monoxide which binds to hemoglobin (creating carboxyhemoglobin)
more than 200 times more tightly than
oxygen and, once bound, prevents it from
accepting oxygen; resulting in cellular
hypoxia even when there is sufficient alveolar oxygen available.
Circulatory (stagnant) Hypoxia
This form of hypoxia occurs when the
body has functional, well-oxygenated,
hemoglobin but is not able to deliver it to
the cells at a rate fast enough to meet
metabolic demands. This occurs in cardiac
pump failure, which can occur in the combat casualties who have sustained blunt
chest trauma, or in those with penetrating
trauma who develop cardiac tamponade.
This cause of hypoxia is also covered in
this chapter in the “Circulation” section.
As stated, the basic pathology in all cases
of histiocytic hypoxia is an inability to
effectively use oxygen that is readily
available. Therefore the initial response of
a casualty with histiocytic hypoxia of any
cause is hyperventilation, although, particularly in the case of cyanide intoxication, apnea can result quickly. Because the
problem in histiocytic hypoxia is not a
lack of oxygen in the blood, in each of
these cases the casualty will not initially
appear cyanotic when exposed to either of
these substances [The word cyanosis refers to the bluish color of the skin that occurs when there is greater than 5 grams of
unoxygenated hemoglobin. It is not related
to cyanide which derives its name from
Prussian Blue, a dye from which hydrogen
cyanide was first extracted].30, 31 In each of
these cases, if a pulse oximeter reading is
obtained early in the poisoning, the reading will be normal. For this reason, unlike
in most other causes of hypoxia, supplemental oxygen is of little benefit, although
Histiocytic Hypoxia
Histiocytic hypoxia is the type of hypoxia
that occurs whenever cellular mitochondria cannot use the adequate oxygen that
is delivered; this can occur for a variety of
reasons. Histiocytic hypoxia is an uncommon cause of significant hypoxia in
the great majority of combat situations.
There are, however, some specific combat
circumstances in which histiocytic hypoxia should be considered as a cause of
hypoxia. Cyanide toxicity is a classic example that may occur in combat casualties
either as a result of exposure to gasses
given off by combustion of certain types
of material or, as the result of a chemical
attack with a blood agent (hydrogen cyanide).29 Although cyanide is a poor chemical weapon for use in open areas because
12
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
if available it should be provided. In both
of these situations prehospital medical
personnel must:
because no specific treatment is
currently available for either of
these conditions at, or near, the
point-of-wounding.
1) Have a high index of suspicion of
histiocytic hypoxia in enclosedspace casualties who are having
breathing problems
2) Avoid becoming personally poisoned
3) Keep the casualty from becoming
more poisoned
4) Quickly evacuate the casualty out
of the area for definitive treatment
In the past some pre-hospital treatment for
cyanide poisoning was available in the
form of amyl nitrite ampules that create
methemoglobinemia to bind cyanide but
these are not now routinely provided because the threat is considered so low that
more harm, as the result of misuse, than
benefit would likely occur.
General Approach to the Management of a Combat Casualty withPpossible
Iimpairment of Ventilation, Oxygenation, and/or Respiration
It is often difficult to determine the cause
of dyspnea because it has multiple causes
and there are a number of receptors that
may produce the subjective feeling of
shortness of breath. Key to correctly diagnosing the etiology of dyspnea in a particular patient is to identify the primary
organ system that is involved. Is the primary cause respiratory, cardiovascular,
both or neither. Michelson et al. in their
article on the “Evaluation of the Patient
with Shortness of Breath”32 state that the
cause of shortness of breath is multifactorial in 27% to 33% of dyspneic patients.
They go on to note that although the standard diagnostic tools of history, physical
examination, and chest radiography have
been found to only be accurate 66% of the
time for all diagnoses they are 81% accurate for diagnosis of the four commonest
causes of dyspnea (asthma, chronic obstructive pulmonary disease, interstitial
lung diseases, and cardiomyopathy);32, 33
since none of these causes of dyspnea are
likely to be the cause of dyspnea in combatants on a battlefield it is unclear how
effective these traditional methods of di-
Initial Assessment and Management
of the Thoracic Wounded Casualty
The pre-hospital evaluation of the thoracic
wounded combat casualty is critically important. First, and most important, a rapid
and accurate assessment is essential to
identify immediately life threatening problems such as tension pneumothorax and
critical hypoxia, so that these can be immediately addressed, and when possible,
corrected. Second, while a fair number of
thoracic wounded combat casualties have
injuries that mandate urgent evacuation
many have injuries that are either superficial or at least stable. While seriously
wounded casualties may need urgent
evacuation to ensure survival, the second,
and larger group, may not need evacuation
at all; or at least their evacuation can
safely be delayed until more favorable
circumstances exist. Depending upon the
combat situation some of this latter group
might reasonably be returned immediately
to combat-related activities.
13
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
any severe thoracic-injured casualty. Injury to the chest wall produces pain on
inspiration so to minimize pain, motion is
restricted. Thus, thoracic wounded casualties usually present with a rapid pulse and
rapid but shallow respirations. When a
tension pneumothorax is present the signs
and symptoms of fear, restlessness, distension of neck veins, extreme dyspnea and
pronounced cyanosis, tend to be dramatic
and unforgettable7(p.157)
agnosing dyspnea would be in a combat
setting.
History
If the thoracic injured casualty is awake
and able to answer questions certain information should be sought. The presence
or absence of pain and its location and
relation to respiration should be determined. Difficulty breathing and whether
or not the difficulty is increasing or decreasing is also important. Has the casualty coughed up blood and if so, how
much? Has the casualty felt nauseated and
vomited and when did he last eat? Nausea
and vomiting, when present, suggest a
thoraco-abdominal injury because these
symptoms are uncommon in the casualty
with only a thoracic wound.34(p.417) Was
the casualty unconscious and if so for how
long? Was the wound ever “sucking”?
What position was the casualty in when
hit and by what type of missile? The position of the patient when injured, type of
missile and proximity to any explosion are
important in arriving at a final decision as
to the probable intra-thoracic lesion; only
by knowing these factors is it possible to
visualize the probable injury.34(p.419) All of
these questions can be asked in a few
moments and they often yield a surprising
amount of useful information.
Accurate pre-hospital evaluation of thoracic wounded casualties is difficult. In his
Civil War Manual of Military Surgery, Dr.
Chisolm, a Confederate surgeon, pointed
out that it is often difficult to detect even
serious injury to the lungs and noted that
there is no one symptom that is sufficient
to make the diagnosis.1(p.281) More recently, in 2002, Eckstein et al.35 stated that
while shortness of breath and chest pain
are the most common presenting complaints of pneumothorax, the appearance
of patients with pneumothorax is highly
variable and can range from acutely ill
with cyanosis and tachypnea to misleadingly healthy appearing. They also noted
that there may be no correlation between
presenting signs and symptoms and the
degree of pneumothorax.35
This said, more recently Forsee34(p.422)
noted that,
Physical Examination
“Fortunately, most foreign objects
travel in a straight line from entrance
to exit, entrance to lodgement. The voluminous literature on the erratic
course of missiles within the body has
tended to over-emphasize the exceptional case that takes a bizarre course
due to striking a rib or other bony
structure. The explanation of most peculiar foreign body tracks is found by
questioning the patient regarding the
position he was in when injured. When
the patient with a foreign body within
The rib cage imposes definite limitations
on the size of the thoracic cavity so any
expanding space-occupying medium (e.g.
air and/or blood) can seriously disrupt the
normal function of the heart and lungs.
Both pneumo and hemothorax can produce similar mechanical effects. By interfering with cardiac return and pulmonary
expansion they reduce the volume of circulating blood and decrease oxygen saturation. This almost invariably produces an
increased cardiac and respiratory rate in
14
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
the thorax that shows no wound of entrance other than the one over the deltoid tubercle of the arm tells the examiner that he was lying on the ground
with his arm extended along the side
of his head, the course of the missile is
no longer mysterious...[T]he most reliable information is obtained by projecting the course of the missile.”34(p.422)
deep respirations suggest ongoing hypoxia. Rapid and shallow respirations
suggest pain on deep inspiration or inability to take a deep breath. Stridor and/or the
use of the accessory muscles of respiration
usually indicate some obstruction to airflow. Rapid, rattling respirations with frequent ineffectual coughs, indicate that the
patient is having difficulty maintaining a
clear airway34(p.420)
Although the signs and symptoms present
in a thoracic wounded casualty and the
physical examination may be misleading,
certain clinical findings should be sought.
Most important is the general appearance
of the patient. If there are signs of cerebral
anoxia such as unconsciousness, agitation,
or irrational behavior the need for prompt
and adequate therapy is great. It should be
noted that cyanosis is a sign of fairly advanced anoxia so if any cyanosis is detected it is usually an indication that the
casualty needs prompt resuscitation.
Measures to decrease anoxia such as thoracentesis for pneumothorax and administration of oxygen should be initiated before the appearance of cyanosis. It is important, however, to recognize that when
there is severe blood loss cyanosis may
not be detectable due to the lowered hemoglobin content of the blood.34(p.420) For
cyanosis to be visible there must be at
least 5 grams of deoxyhemoglobin per 100
ml of blood present36 [before cyanosis
would be present in a patient with a hemoglobin of 10 more that 50% of that hemoglobin would have to be deoxygenated].
Difficulty breathing may either be due to
actual “shortness of breath” or, more
commonly, to being “unable to take a
good breath.” The former suggests hypoxia, which may be caused by any one,
or a combination, of causes (hypoxemic,
anemic, stagnant, and histiocytic) while
the latter results from pain associated with
breathing. In combat casualties without
severe blood loss, “shortness of breath” is
usually caused by pathology in the pulmonary parenchyma.”34(p.417)
Some amount of hemoptysis is to be expected in almost every case of penetrating
thoracic injury. But, as Fraser noted based
on his experience in the Crimean War,3
“[Expectoration of blood] is no certain
indication that the [lung] has a [penetrating injury]…spitting of blood is a very
deceptive diagnostic sign of lung wound.”
However, “When [blood] is rapidly
brought up by the mouthfuls it becomes an
important symptom [of penetrating injury
to the lung].”3(p.284) While hemoptysis frequently indicates the presence of penetrating chest injury it is also commonly present when there has been blunt chest
trauma or blast injury. Although the
amount of blood coughed up is variable,
generally the larger and more severe the
injury, the greater the quantity of hemoptysis. When there is a large amount of
hemoptysis the airway may become obstructed so attention must be paid to the
airway.34(p.417)
The type and character of respirations are
particularly important in the assessment of
thoracic wounded casualties. Assessment
of ventilatory pattern can offer important
clues as to the extent of injury in thoracic
wounded casualties. While fear and exertion can cause an increase in the rate and
depth of respiration, persisting rapid and
15
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
ignored but the busy, noisy, and stressful
pre-hospital environment is rarely conducive to an effective, meticulous, examination. In this setting minor deviations from
normal are generally unimportant. Attention should primarily be paid to the patient
as a whole and to his gross abnormalities.34(p.420)
The presence or absence of loss of consciousness and it’s duration in thoracic
wounded combat casualties has been reported to be helpful in both diagnosis and
prognosis. According to Forsee,
“A short period of unconsciousness is
not infrequent when injury has been
caused by a high explosive shell.
Longer periods, especially if preceded
by consciousness, are apt to be due to
cerebral anoxia and are therefore of
the utmost importance, both in regard
to the severity of the wound and from
a prognostic standpoint. Unconsciousness of more than momentary
duration means that there is cerebral
concussion, severe blood loss, or
cerebral damage from prolonged anoxia. Maniacal manifestations, frequently a sign of severe anoxia, may
likewise be present and this oxygenwant must be combated vigorously.”34(p.419)
Auscultation
Auscultation is one of the primary methods for assessing pulmonary status, even
in prehospital settings, but, as will be discussed later in greater detail, auscultation
is often inaccurate even when performed,
by a physician. Chen and colleagues37 in
their assessment of auscultation note that
optimal physical examination of the chest
may be impeded by a noisy resuscitation
area, an overly rapid initial examination,
and inattentiveness to the task.37 All of
these are problems often present in an
emergency department setting35 and they
are certainly present in the combat environment.
If there is either a history of, or obvious,
“sucking” (exchange of air) through the
chest wound it can be assumed that the
pleura have been penetrated; the absence
of sucking, however, says nothing about
the course of the missile or the damage it
may have produced.34(p.419)
Penetrating injury of the chest, especially
when the intercostal vessels, lung parenchyma, or pulmonary vessels are injured,
generally results in a hemothorax. As
noted earlier, physical findings tend to be
normal in patients with a small pneumothorax.38-40 The characteristic physical
examination findings associated with a
pneumothorax are more likely to be present when lung collapse is greater than
25%.37, 41
In a pre-hospital setting assessment for
certain gross physical findings may provide more accurate information regarding
the status of thoracic-wounded casualties
than might the more “refined” methods
commonly used to evaluate such patients
in civilian emergency departments. For
example, checking the position of the trachea in the suprasternal notch or assessing
the position of the apical impulse of the
heart may be more effective at diagnosing
a clinically significant hemopneumothorax
than very careful, time consuming percussion and auscultation. In a more appropriate setting the latter methods are not to be
In their study of the efficacy of auscultation in detecting hemo and hemopneumothorax Chen et al. found that auscultation to detect these injuries, while having a
fairly high specificity and positive predictive value, had a low sensitivity (58%).
Their conclusion was that hemopneumothorax and hemothorax, especially
when caused by gunshot wounds, are
16
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
likely to be missed by auscultation. They
did, however, note that because of the
fairly high specificity of auscultation, decreased breath sounds, together with overlying penetrating trauma, is a reliable indication of the need for tube thoracostomy
and thus can be used to make this decision
before chest radiography.37
diagnostic accuracy of 47% for pleural
effusion, 75% for alveolar consolidation,
and 72% for alveolar-interstitial syndrome. By comparison lung ultrasonography had a diagnostic accuracy of 93% for
pleural effusion, 97% for alveolar consolidation, and 95% for alveolar-interstitial
syndrome.
Another study by Hirshberg et al., found
that while auscultation may not be effective at picking up small hemo and pneumothoraces it is fairly effective (96% sensitive) at picking up larger (and more
clinically important) collections of air and
blood in the chest.42 In 1990, Thomson et
al.43 reached a similar conclusion. They
found that physical examination was able
to detect large collections of air and fluid
in the chest (96% and 94% respectively)
and thus it could be used to guide management of thoracic wounded casualties. It
should be noted, however, that 92% of
patients in their study had sustained knife
wounds making this population considerably different from that of a population of
combat casualties.43
Not only was lung ultrasound more accurate than auscultation and chest radiography but it was able to quantify the extent
of lung injury. This study concluded that
bedside lung ultrasonography is highly
sensitive, specific, and reproducible for
diagnosing the main lung pathologic entities associated with ARDS and noted that
it should be considered an alternative to
portable chest x-ray and chest computed
tomography.44 Ultrasound of the chest is
also increasingly being used in hospital
settings to make the diagnosis of pneumothorax and, as portable ultrasound devices become lighter and more durable,
ultrasound is making its way to the forward edge of the battlefield.44-48 Until a
device can be developed that will give a
relatively unskilled medic a simple yes-no
answer about the presence or absence of
pneumothorax this technology will not be
of much use at the point of wounding; but
perhaps this capability is not too far in the
distant future.
Use of ultrasonography to detect lung
injury
Although ultrasound is not a device likely
to be used at, or near, the point-ofwounding anytime in the near future, ultrasound is an effective diagnostic tool for
intra-thoracic injury and it is being increasingly used far forward. A prospective
study by Lichtenstein et al.44 compared the
diagnostic accuracy of lung ultrasound,
auscultation, and bedside radiography
with a gold standard of thoracic computed
tomography. Pleural effusion, alveolar
consolidation, and alveolar-interstitial
syndrome were evaluated. They found that
auscultation had a diagnostic accuracy of
61% for pleural effusion, 36% for alveolar
consolidation, and 55% for alveolarinterstitial syndrome. Portable x-ray had a
Another technology being developed for
far forward diagnosis of pneumothorax is
micropower-impulse radar (MIR). This
technology is being developed at the Lawrence
Livermore
National
Labs.
(http://www.biomec.com/projects/pneu
mo.html) and may result in a pneumothorax detection device that is smaller, more
durable, and easier to use than ultrasound
technology.
17
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
moglobin, which absorb light at, or near,
these wavelengths. When present in the
blood these substances will indicate a
falsely high, or low, percent hemoglobin
saturation. Carboxyhemoglobin, which
may be present in combat casualties who
are exposed to combustion in a closed
space [e.g. combat vehicles, caves, buildings, etc…], absorbs light at very nearly
the same wavelength as oxyhemoglobin,
giving a falsely high pulse oximetry reading. Thus when carboxyhemoglobin is
present it may lead to an incorrect assumption that a combat casualty is adequately oxygenated when, in fact, this may
not be the case. Methemoglobinemia,
which would be unlikely to be present in
combat casualties in the field, markedly
increases absorbance of light at both 660
and 940 nm and produces a pulse oximeter
reading that tends toward a reading of
85% saturation (regardless of true oxygen
saturation). Clinically this usually means
that when methemoglobin is present the
pulse oximeter reading is falsely low.
Pulse Oximetry
Today pulse oximetry is widely available
for use in patient assessment. Indeed the
patient’s oxygen saturation is now commonly referred to as the “fifth vital sign”
and the measurement of oxygenation by
pulse oximetry is considered standard of
care in emergency departments in the
United States. Pulse oximeters have gotten
smaller, lighter, and more durable; they
are increasingly used in the pre-hospital
environment and are being used today by
some military medical personnel at, or
near, the point-of-wounding.
Adequacy of oxygenation (but not of ventilation) is generally determined by a pulse
oximetry reading above 90%. In most settings pulse oximetry is very effective at
assessing the adequacy of oxygenation. It
should be noted, however, that pulse oximetry does not directly measure the
amount of oxygen bound to hemoglobin.
Pulse oximetry functions by relying upon
the Beer-Lambert law which states that the
concentration of a light-wave absorbing
substance (in the case of pulse oximetry,
oxy- and deoxy-hemoglobin) in solution
can be determined from the intensity of
light that is transmitted through that solution, if the intensity and wavelength of
incident light, the transmission path
length, and the characteristic absorbance
of that substance at a specific wavelength
(deoxyhemoglobin absorbs at 660 nm and
oxyhemoglobin absorbs at 940 nm) are
known.
Other factors, more common in combat
casualties, can also influence pulse oximeter readings. These include motion artifact
(some pulse oximeters are less affected by
motion artifact than others), hypotension,
anemia, and hypothermia. Finally, it is
important to note that pulse oximetry only
assesses, indirectly, the percent of hemoglobin that is saturated with oxygen; it
does not confirm that oxygen is being delivered to, and consumed at, the cellular
level. In cyanide poisoning, for example,
the oxygen saturation measured by pulse
oximetry may initially be near normal despite severe cellular hypoxia caused by
cyanide’s disruption of cellular oxygen
metabolism.
Because this is how oxygenation is measured pulse oximetry can give a false reading in a variety of situations. There are
substances other than oxy- and deoxyhemoglobin, such as carboxy- and methe-
18
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Pre-Hospital Assessment of Thoraco-Abdominal Injury
Physical exam evidence of abdominal injury in casualties with thoraco-abdominal
wounds is helpful, but not completely reliable, in making the diagnosis of thoracoabdominal injury. Many thoracic wounds,
without associated abdominal injury,
cause pain and spasm of the upper abdomen while many patients with abdominal
injury present with limited physical findings, especially if just solid organs have
been injured.34(p.424) Following his experiences in the Spanish Civil War Jolly7 also
noted that abdominal rigidity often accompanies many chest wounds and that
this often incorrectly suggests the presence of abdominal penetration. These diagnostic challenges notwithstanding, Jolly
did note that there are some differences
between the abdominal findings in patients with pure thoracic wounds and those
having wounds that involve the abdomen
as well. He pointed out that, “The rigidity
associated with abdominal wounds usually
develops bilaterally, whereas abdominal
rigidity from a chest wound is usually
confined to the rectus muscle of one side.
He went on to say that, “Abdominal rigidity associated with [isolated] chest wounds
tends to be intermittent, [with] some relaxation usually occurring with inspiration…[while]… [a]bdominal wounds are
usually accompanied by vomiting or
[belching].7(p.156)
Assessment of Shock in Thoracic
Wounded Casualties
The assessment of shock in the thoracic
wounded casualty may be complicated by
the fact that hypoventilation in such a patient, with accumulation of excessive CO2,
may act to elevate the blood pressure.
Forsee noted after World War II that “Inexperienced observers might be lulled into
a false sense of security by this elevated
blood pressure.” He felt that because there
is no one pathognomonic finding of shock
the general clinical impression of an experienced medical officer may be a better
guide than any specific physiologic parameters that can be measured and recorded numerically.34(p.432) This does not
mean, however, that the physiologic parameters of pulse, blood pressure, and rate
and depth of respirations should not be
measured but it should rather serve as a
warning not to be lulled into a false sense
of security by normal appearing vital signs
especially in patients with thoracic
wounds.
General Management of Thoracic
Wounded Casualties
Basic pre-hospital management of combat
casualties with penetrating chest wounds
remains largely unchanged since at least
the Spanish Civil War. At the end of that
war Maj. Douglas Jolly, in his book, Field
Surgery in Total War, stated that, “The
most useful pre-hospital treatment of the
thoracic wounded casualty is the application of a large, occlusive dressing to the
open pneumothorax.”7(p.158)
While there are no pathognominc signs of
esophageal injury pain in the area of the
posterior thorax, pain radiating into the
lumbar area, and/or substernal pain on
swallowing all suggest injury to the
esophagus.34(p.424)
In WWII medical aidmen were originally
instructed to apply an occlusive dressing
19
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
sion pneumothorax but there is no data to
prove that it does. Proponents of sealing
the dressing on four sides argue that the
greater problem in applying a dressing
over a chest wound in the heat of combat
is getting the dressing to remain attached
to the chest wall, sealed on any side at all.
They feel it unlikely that the chest wall
dressing, thus taped, would cause a tension pneumothorax.
to only those wounds that were clearly
sucking. Later, because it was found that
penetrating chest wounds might suck only
intermittently, medics were instructed to
treat all chest wounds in this way. Upon
reaching a battalion aid station the temporary dressing was to be replaced by a larger, Vaseline impregnated dressing, preferably one at least twice the size of the
wound, held in place by adhesive tape.
If the wound was very large, large sutures
were placed through the skin and tied over
the dressings. These measures where felt
to be effective for 5 or 6 hours, or longer.
After a prolonged period, when the Vaseline-impregnated gauze dressing had become caked with blood, and was no longer
pliable enough to act as a one-way valve,
a needle with a flutter valve attachment
was usually placed in the second interspace parasternally to provide for the escape of air and prevent development of a
tension pneumothorax.49(p.9)
3-sided Occlusive Dressing
Current thoracic wound therapy for sucking chest wounds, as promulgated by The
Committee on Tactical Casualty Care in
the Military Medicine Chapter of the Prehospital Trauma Life Support Manual is
that such wounds “Should be treated by
applying a vaseline gauze during expiration, covering it with tape or a field dressing, placing the casualty in the sitting position, and monitoring for development of
a tension pneumothorax .50(p.1)
A device called the Asherman Chest
SealTM marketed for the purpose of sealing
sucking chest wounds solves the dilemma
of three sides versus four. It consists of a
flexible 5.5 inch diameter disc, coated
with a strong adhesive, with a central hole
that exits through a flexible one-way
valve.
The argument as to whether chest wound
dressings should be sealed on three or four
sides rages on today without a definitive
answer; either is probably acceptable.
Proponents of sealing on three sides
[which includes the American College of
Surgeons Committee on Trauma51] argue
that the dependant side should be left open
to allow air to escape on exhalation. This
technique should, at least theoretically,
help to prevent the development of a ten-
Asherman Chest Seal
20
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
thoracic wounded casualties, remains to be
delineated. While oxygen is used with
abandon in the civilian pre-hospital setting, there are potential problems with the
widespread use of oxygen in the combat
zone. Increased levels of oxygen significantly increase the risk of serious fire52-57
and widespread use of oxygen in the prehospital areas would create a significant
logistical challenge, not the least of which
is the bulk and weight of both compressed
gas oxygen cylinders and oxygen generators.
The disc is designed to be applied with its
opening directly over a chest wound so
that any air escaping from the wound under pressure will pass through the one-way
valve; air is thus prevented from entering
the chest when negative intrathoracic
pressure is generated by inspiration. This
device is commonly used today by front
line medics and corpsmen; its principle
advantage over more standard methods
most probably being the very effective
adhesive that seals the disc to the chest
wall.
Ideally oxygen would be reserved for
those casualties who would obtain real
benefit from its administration; specifically all those having a decreased intraalveolar partial pressure of oxygen. As
noted earlier, inadequate ventilation can
lead to hypoxia that is correctable by the
administration of oxygen but the fundamental problem in hypoventilation is hypercarbia and improved ventilation, even
without supplemental oxygen, will correct
both the hypoxia and the hypercarbia.
It is important for forward area combat
medics and corpsmen to understand that
the aim of surgical treatment of thoracic
wounded casualties is mainly directed toward restoring normal respiration. The
main focus of forward care therefore
should be to minimize the period during
which hypoxia may produce cerebral
damage. Once normal oxygenation and
ventilation are restored, the time to surgery is generally not a matter of great importance for most thoracic-injured casualties who survive to be treated.34(p.426)
Inadequate ventilation, with its attendant
hypercarbia, is a common problem in thoracic- wounded combat casualties. As discussed in detail later, hypoventilation in
thoracic wounded combat casualties is
commonly caused by pain on inspiration
so adequate pain control is vital to improved ventilation in such patients.
Oxygenation and Ventilation of
Thoracic Wounded Casualties
The greatest hazard to the soldier with a
thoracic wound is hypoxia. Thus, everything that can be done to increase the
amount of oxygen transported by the
blood is indicated. Ideally oxygen should
be started on each thoracic wounded casualty as soon as it can be provided and it
should be continued until the casualty has
been fully evaluated. At this point the further use of oxygen can be based upon the
presence or absence of a condition that
will clearly benefit from it use.34(p.437)
Also discussed in detail is the important
role that proper positioning plays in helping to prevent hypoventilation in thoracicwounded combatants. Only a very small
number of thoracic wounded casualties
require assisted ventilation. If a thoracic
wounded casualty has to be intubated and
ventilated in a pre-hospital setting survival
is unlikely; thus, for the great majority,
penetrating thoracic injury does not, of
itself, constitute a reason for intubation.
Despite this general recommendation the
exact role of pre-hospital oxygen, even in
21
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
oxygenation by transporting them in the
prone position. Following a 1976 study
that showed that placing patients with
acute respiratory distress syndrome in the
prone position significantly improved
oxygenation this position has been used
with increasing frequency in the intensive
care unit treatment of such patients.59 Possible reasons for the apparently improved
oxygenation of patients in the prone position include:
Patient Positioning for Optimal
Ventilation and Respiration
Responsive patients having respiratory
difficulty reflexively seek a body position
that optimizes ventilation. When patients
do this, health care providers should help
them achieve this position and most certainly they should not interfere with their
efforts in this regard. Asthmatics with
acute bronchospasm, for example, seek a
position that is referred to as the “Tripod”
position -- sitting up, feet hanging down
freely, and leaning forward slightly with
hands placed on thighs and shoulders
hunched up. This position optimizes ventilation by minimizing the work of breathing and maximizing the efficiency of the
accessory muscles of respiration. Unless
contraindicated combat casualties with
breathing problems should be transported
sitting up in a Semi-Fowlers position to
optimize ventilation.
1) An increase in end-expiratory
lung volume60
2) Better ventilation-perfusion
matching61
3) Regional changes in ventilation
associated with alterations in
chest-wall mechanics.62, 63
These studies indicate that as many as
sixty to seventy percent of ARDS patients
obtain improved, sometimes significantly
improved, oxygenation when in the prone
position. A moderately large 2001 Italian,
multi-center, randomized trial64 that compared conventional supine treatment of
patients with acute lung injury or acute
respiratory distress syndrome with those
placed in a prone position also showed
improved oxygenation in prone patients.
It should, however, be noted that in this
study despite improved oxygenation in the
prone patients there was no difference between the two groups in overall survival.
What is often under-appreciated is the
negative impact on breathing that is
caused by strapping a patient down on a
backboard during transport. Simply lying
supine reduces the efficiency of breathing
and applying straps across the chest restricts free excursion of the chest. Concern
for the cervical spine should not be allowed to over-ride optimizing ventilation/respiration, especially in the combat
casualty with a penetrating injury in whom
the risk for an unstable cervical spine injury is extremely low [see “Disability”
section for a more detailed discuss of this
issue].58
Fluid Resuscitation of Thoracic
Wounded Casualties
The immediate cause of death in most thoracic wounded casualties is hemorrhage
from the heart or great vessels. Slower but
persistent hemorrhage can cause delayed
death; a common bleeding site being the
intercostal vessels. In the past hypotensive
casualties with penetrating chest wounds
were aggressively fluid resuscitated but
today, as discussed in detail in the “Circu-
As indicated in the discussion about the
airway, unresponsive patients should be
transported in the prone (not supine) or
“rescue” (lateral decubitus) position to
prevent aspiration. Unresponsive patients
having
problems
with
oxygenation/respiration (not those with ventilation
problems) may actually have improved
22
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
ity of restarting a previously stopped hemorrhage.”65
lation” section, limited fluid resuscitation
of such casualties is recommended. As
Jolly noted as long ago as the Spanish
Civil War, “Intravenous saline or transfusions should not be given in the First Aid
Post or Classification Post. These active
measures serve only to increase the outpouring of blood from the hidden vessels
in the chest wall into the pleural cavity.”7(p.158)
Interestingly it appears that as long ago as
the Civil War, the benefits of sustaining
(or even inducing) hypotension, in thoracic-wounded casualties were recognized.
Dr. Chisolm, a senior Confederate surgeon, stated that, “It is not surprising…that the [thoracic-wounded] patient
should soon become cold, pale, and faint –
with feeble, small and irregular pulse,
and…tendency to syncope. This is nature’s effort to check further [blood]
loss…”1(p.287)
In 1945, Forsee pointed out that not all
chest wounded casualties who are hypotensive have significant blood loss and
he cautioned that, “The inexperienced are
apt to institute rapid blood replacement
which may be fatal to an already unbalanced cardiorespiratory system.” He suggested that, “Intravenous therapy should
be withheld in the thoracic casualty until it
has been determined that he is suffering
from blood loss.”34(p.426)
Dr. Chisolm went so far as to suggest that
“The surgeon [should try]…to induce this
condition for a similar purpose…[and]
[n]otwithstanding
the
hemorrhage,
[should] open a large vein and draw away
blood, if possible, to syncope.”1(p.290)
While it is clear today that it was erroneous to conclude that inducing further
blood loss in bleeding, and already hypotensive, thoracic-wounded casualties
would be beneficial, the basic observation
that hypotension can be beneficial does
now have scientific support. [See “Circulation” Section]
It should, however, be noted that hypotension in the thoracic wounded combat
casualty may be caused by cardiac tamponade and this condition is at least temporarily improved by fluid administration
even when there has been no significant
blood loss.
In the past it was suggested that when
there is ongoing intrathoracic hemorrhage
and a pneumothorax, the pneumothorax
should not be relieved. This was based on
the mistaken notion that the increased intrathoracic pressure associated with the
pneumothorax would help to control
bleeding. Forsee noted that, “Bleeding
from the pulmonary parenchyma will stop
of its own accord in the vast majority of
cases, and the relatively small pressure
difference that may exist in the pleural
space due to a pneumothorax is not efficacious in checking a hemorrhage from one
of the systemic vessels. Many more errors
are made by not aspirating the chest, than
by aspirating it, with the remote possibil-
While vigorous saline resuscitation of thoracic wounded casualties is not advised,
when the amount of bleeding into the
chest is large and the patient is hypotensive, early administration of blood, when
it is available, is recommended. If autotransfusion is available and there is not a
thoraco-abdominal injury, larger hemothoraces, if less than 24 hours old, can be aspirated and autotransfused.34(p.427), 66
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Clifford C. Cloonan, MD
Breathing
once peripheral circulation is restored;
when this happens the patient may become
unexpectedly apneic from morphine intoxication. Excessive administration of
morphine can occur during combat; the
aforementioned scenario being just one
such way that this can occur. During
World War II four percent of patients received over one-half grain (30 milligrams)
while 0.5% had one grain (60 milligrams)
or more during the pre-operative period.34(p.412-450)
Relief of Pain in Chest Wounded
Casualties:
Pain is almost universally present in chest
injury. Key to proper pain management in
the chest wounded casualty is an understanding that pain does not arise from the
lung but originates in the thoracic wall.
One approach to pain management in the
thoracic wounded casualty is to interrupt
painful stimuli near their origin with local
anesthesia of the intercostal nerves that
supply the painful area. Intercostal nerve
block is a simple, and effective means of
accomplishing pain relief in patients with
chest wall pain; it is even superior to opiate analgesics and is without their adverse
effects. The main risk of an intercostal
nerve block is the creation of a pneumothorax. If a pneumothorax is already
present, this is not a concern. If the painful
segment of the thoracic wall is blocked,
including nerves above and below the site
of the injury, lasting pain relief usually
results.
Therapeutic Interventions that may
Contribute toHhypoxia - Introduction
of Dead Space
Some therapeutic interventions can actually contribute to hypoxia and hypercarbia. Intubation and artificial ventilation,
with its attendant use of artificial airway
tubing increases dead space. This “iatrogenic” dead space is added to anatomic
dead space, the conductive zone of the
airways that consist of the upper airway,
trachea, bronchi and bronchioles. This
space has a transport function only and
does not participate in gas exchange. The
volume of gas that fills anatomic dead
space, about 150 ml, accounts for about
30% of a normal tidal volume of 500 ml.
While it takes energy to transport this
dead space volume back and forth during
respiration, none of the oxygen in these
conductive airways is extracted. In some
pathologic situations, such as pulmonary
embolus, there is an increase in the
amount of un-perfused but ventilated lung
and these areas also contribute to dead
space. Significant pathologic dead space
contributes to hypoxia as described earlier.
In some critical patients the energy wasted
in the effort to move dead space gas back
and forth can have clinical consequences.
Morphine, while effective, should be administered with caution. Symptoms of
cerebral anoxia, such as restlessness and
agitation, may be misinterpreted as pain,
resulting in the repeated administration of
morphine. The situation with the highest
risk of inappropriate repeated administration of morphine is when the casualty is
hypotensive, with poor peripheral circulation. In such a situation, with decreased
peripheral blood flow, morphine given
subcutaneously or intramuscularly, may
not be fully absorbed into the blood
stream. This means pain will be unrelieved; a situation that frequently leads to
the further administration of morphine.
This may result in patients being given
multiple doses of morphine without much
benefit. The major hazard from such a
situation, however, arises not from inadequate pain relief but from the later absorption of this depot of unabsorbed morphine
As noted above, medical interventions,
such as intubation, contribute to dead
space by increasing the volume of gas in
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Clifford C. Cloonan, MD
Breathing
parenchyma, (6) injury to structures in the
mediastinum and/or (7) injury to the diaphragm. 67
conductive airways. In patients with otherwise healthy lungs the volume of gas
contained in an endotracheal tube is generally not clinically significant but in patients with compromised respiration and
pathologically increased dead space the
small increase in dead space from a long
endotracheal tube can be significant, especially during long term ventilation. The
longer the length of tube before it is
vented the higher the CO2 and the lower
the oxygen content in the lungs. For this
reason, the dead space volume of connecting tubes or hoses should be as small as
possible -- this means use a short tube
whenever possible.
Blunt Chest Trauma (rib fractures,
flail chest, pulmonary contusion)
Blunt injury as a percent of all U.S. combat-associated injury appears to be increasing. During the early part of Operation Iraqi Freedom 39% of 294 battlefield
casualties transported outside of Iraq for
medical care had sustained blunt/motor
vehicle collision injuries.68 Satava notes
that because of the use of body armor
mortality is primarily caused by direct
head and neck injury or “overwhelming”
force to the trunk, with thoracoabdominal
injuries occurring from blunt rather than
penetrating injury.69
Specific Mechanisms of
Combat-related Injury Associated
with Impairment of Ventilation,
Oxygenation, and/or Respiration and
their Management
There are likely several reasons for this.
First, large numbers of troops are now
routinely moved by motorized air, land
and sea transport and injuries sustained
during transport are predominantly blunt.
Second, urban combat is becoming increasingly common as the percentage of
the world’s population that lives in cities
increases70 and with this type of combat
has come a concomitant increase in the
number of crush injuries from collapsing
buildings and injuries associated with falls
from a height. Finally, the widespread use
of body armor has significantly reduced
the number of penetrating injuries to protected areas, most specifically, the chest.
Kevlar also reduces the severity of blunt
injury. It is widely used by athletes who
are at risk of blunt chest trauma because of
its ability to attenuate blunt chest injury.
Although body armor use by combatants
does reduce the total number of blunt
trauma injuries the greatest benefit of
body armor in a combat environment is in
reduced penetrating injury. Because it so
effectively reduces the risk of penetrating
injury the overall effect of increased body
As previously noted injuries outside the
thorax can impair cellular oxygenation.
Neurologic injury to the head, phrenic
nerve, or nerves to the accessory muscles
of muscles of respiration can all impair
ventilation and lead to hypercarbia and
hypoxia. In addition, as emphasized earlier, loss of hemoglobin (hemorrhage) and
cardiac injury can result in there being an
inadequate flow of oxygenated hemoglobin to the cells. As the management of
these problems is discussed elsewhere the
focus of the following discussion will be
on injuries to the thorax that impair ventilation and oxygenation.
Injuries to the thorax that can impair oxygenation and ventilation in combat casualties include: (1) neurologic injury (2) injury to the upper and/or lower airways (3)
injury to the chest wall (4) injury involving the pleural space (5) injury to the lung
25
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
rarely important. The two important management issues in patients with presumed
rib fractures are maintenance of pulmonary function and pain management. Pain
management is important irrespective of
whether one or more ribs are actually fractured. Oral pain medications are usually
sufficient for most combatants with symptoms and findings suggestive of rib fracture(s). To the extent possible combatants
with simple rib fracture(s) should be encouraged to continue their duties and deep
breathing should be recommended to help
prevent atelectasis and pneumonia. The
general recommendation is that chest
binders, belts, and other restrictive devices
should not be used because they limit
chest excursion (which is how they reduce
pain), and promote hypoventilation with
its attendant risk of atelectasis and pneumonia. In young, fit, previously healthy
combatants the risk of atelectasis and
pneumonia following a single, uncomplicated, rib fracture is very low so in this
group the use of a rib belt may not be unreasonable if it allows them to remain
functional.
armor use is likely a relative increase in
the portion of combat-associated injuries
caused by blunt injury [not an increase in
total number of blunt trauma injuries].
Although body armor may prevent penetrating chest injury serious blunt injury
behind the armor can still occur when armor is struck by a high energy object.
Body armor can thus convert what could
have been a fatal penetrating injury into a
behind-armor blunt injury when a combatant is struck with a high energy missile
that does not penetrate.
There are also circumstances in which
fragments, particularly large fragments,
can cause blunt, not penetrating injury. As
noted by Chisolm during the Civil War,
“The lung…may be severely injured when
no perforating wound exists. A blow by a
spent ball, or a fragment of a shell, may
make a superficial wound or bruise in the
skin, and yet may shatter one or more ribs,
driving the spiculae into the lung, lacerating to a greater or less extent its substance.
Even without fracture of the ribs, the concussion or blow may have been sufficiently great to have caused irreparable
injury to the lung.”1(p.282)
Pneumonia can occur as a complication
following rib fracture although this is generally not a serious risk in previously
healthy combatants. Bulger et al74. found
that among patients with rib fracture(s)
admitted to a Level I trauma center pneumonia occurred in 31% of elderly versus
17% of young (p < 0.01) patients. More
significantly the mortality from pneumonia following rib fracture was over twice
as high in the elderly as in younger patients. Not surprisingly, mortality and
pneumonia rates were found to increase as
the number of rib fractures increased. For
each additional rib fractured the odds ratio
for death rose 1.19 and for pneumonia it
rose 1.16 (p < 0.001).74 As the average age
of combatants goes up this may become
an increasingly important issue in combat
casualties. Many casualties with rib frac-
Rib Fractures
In civilian settings, where blunt trauma
dominates, rib fractures are the most
common type of chest injury.71 Although
the precise incidence is unknown, studies
have shown that most civilian rib fractures
occur as the result of motor vehicle accidents.71-73 The exact incidence of rib fractures among combat casualties is unknown. In World War II about 75 percent
of all combat-incurred penetrating and
perforating wounds of the chest were associated with compound fractures of one
or, more often, several ribs.49
Accurate diagnosis of rib fracture(s) in the
forward area is difficult but fortunately
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
chest trauma and its related complications
are responsible for up to twenty-five percent of all blunt trauma mortality.75 In
multi-trauma victims, mortality in association with pulmonary contusion can be as
high as thirty-five percent.81 The exact
incidence of death in patients with isolated
pulmonary contusion is difficult to know
because concomitant injury is almost always present-- usually it is reported to be
between 10 and 25 per cent.82-84 With
more than 200,000 cases of blunt chest
trauma annually, there may be as many as
15,000 deaths due to this cause each
year.75
tures will require narcotic preparations,
but care should be taken to avoid excessive analgesia with its associated sedation
and hypoventilation.
If there is a reasonable question about
whether the rib fracture(s) is/are accompanied by more serious injury or if there is
obvious compromise of the patient’s ability to cough, breathe deeply, and maintain
activity, it would be advisable to evacuate
the casualty to a hospital setting for more
aggressive pulmonary treatment. When
there is significant pain and/or when narcotic pain medications can’t, or shouldn’t,
be administered, intercostal nerve blocks
with a long-acting anesthetic such as
bupivacaine with epinephrine may relieve
symptoms up to 12 hours. Performance of
intercostal nerve blocks obviously requires
that the care provider possess the requisite
skills, knowledge, experience, and equipment to perform this procedure. Pneumothorax is a potential and not rare complication of this procedure.
Although penetrating injuries of the chest
have historically been more common in
combat casualties than blunt injuries, blunt
injuries do occur. In civilian trauma approximately 70 per cent of blunt chest
trauma is the result of motor vehicle accidents.85-87 While blunt chest trauma is still
most commonly caused by motor vehicle
crashes, the increased use of restraints has
decreased severe blunt chest trauma from
22.8 per cent to 9.7 per cent.75
Pulmonary Contusion and Flail
Chest
Blunt chest trauma impairs ventilation by
interfering with the movement of the chest
wall and it often also causes contusion
injury to the underlying lung resulting in
ventilation-perfusion mismatch. Adult
respiratory distress syndrome (ARDS)
complicates 5-20 per cent of patients with
pulmonary contusions.84, 88, 89 The pulmonary contusion patient is at greatest risk of
developing ARDS within the first 24
hours after injury.84 Fortunately ARDS
does not typically develop in combat
casualties at, or near, the point of wounding because it takes time to develop after
serious chest trauma. Acute respiratory
distress syndrome is characterized by a
hypoxemia that does not improve when
supplemental oxygen added.19 Mortality of
ARDS remains approximately 35% despite modern intensive care. Increased
One of the more serious complications of
blunt chest trauma is pulmonary contusion. In civilian settings roughly 70% of
pulmonary contusions are the result of
motor vehicle crashes.75 Other causes include falls from a significant height and
penetrating thoracic injury. While penetrating injury can cause pulmonary contusion it does not do so to the same degree
as blunt trauma. In the Yale trauma registry seventeen percent of patients with multiple blunt trauma injuries had pulmonary
contusion.76 Pulmonary contusion, the
most common pulmonary parenchymal
injury in blunt chest trauma, is present in
30% to 75% of patients with significant
blunt chest trauma.77-80 By contrast, pneumothorax is present in 15% to 50% of patients with blunt chest trauma.73 Blunt
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Clifford C. Cloonan, MD
Breathing
pulmonary contusion. Wagner et al. identified four types of lesions that may be
responsible for causing pulmonary contusion:97
pulmonary hypertension indicates a poor
prognosis in patients with trauma and respiratory failure.19
Rib fractures are very painful and as a result patients with rib fractures usually under-ventilate causing some degree of CO2
retention. A flail chest, resulting from
fractures of three or more contiguous ribs
in two places, causes paradoxical movement of the chest wall during respiration.
On inspiration, as the uninjured portion of
the chest moves outward, the flail segment
is drawn inward by negative intrapleural
pressure; the reverse occurs during expiration. This is the so called “pendelluft”
phenomenon. In the past, hypoxemia and
pulmonary dysfunction associated with a
flail chest were attributed to hypoventilation caused by the reduced efficiency of
ventilation caused by this "pendelluft"
phenomenon.90-92 It has now been shown
that the paradoxical wall motion in flail
chest does not cause air movement from
damaged to normal lung. Minute ventilation and O2 uptake may actually be greater
on the side of the flail segment.67 The
principal cause of hypoxia in flail chest
injured patients is the pulmonary contusion that is always concomitantly present
in this injury.93 When flail chest injury is
present, in addition to pulmonary contusion, there may also be intra-abdominal
injury because significant traumatic forces
are required to fracture multiple ribs.
These associated internal injuries are the
primary cause of the 5% to 7% mortality
rate in patients who have multiple rib fractures.94, 95 In some studies mortality from
flail chest injuries has ranged from 10% to
50% due to the severity of the underlying
injuries.67, 94, 96
•
•
•
•
Type I lesions are caused by compression of the chest wall against
the lung parenchyma – this
mechanism is responsible for most
cases of pulmonary contusion
Type II lesions are caused by a
shearing of lung tissue across the
vertebral bodies.
Type III lesions occur when a
fractured rib, or ribs, injures the
underlying lung.
Type IV lesions occur when
shearing forces across previously
formed adhesions tear the pulmonary parenchyma.
Another proposed mechanism is that differential acceleration of alveoli and bronchial structures causes the alveoli to be
stripped away from bronchioles. Finally,
concussion from a blast wave may also
cause pulmonary contusion by spalling.98
Spalling is what happens when a concussive wave passes through a tissue-gas interface and part of the tissue at the interface is sheared off.75, 99, 100
Although widening of the distance between the alveolar spaces and passing
blood in pulmonary capillaries can contribute to hypoxemia in patients with pulmonary contusion, serious hypoxemia is
primarily due to hypoinflation.84, 101 Ventilation in the area of the contusion may be
decreased by as much as 44 percent.102
Although not generally an issue at, or
near, the point-of-wounding, atelectasis
and infection can also be important contributors to hypoxia at 24 to 48 hours after
injury.101-103
The basic lesion in pulmonary contusion is
disruption of the parenchyma. There are
several mechanisms that have been proposed to explain the pathophysiology of
By reducing blood flow to underventilated areas of contused lung, hypoxic
28
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Close respiratory monitoring of patients
with serious blunt chest trauma with continuous pulse oximetry and reexamination
must be maintained because, as pointed
out earlier, about half of all respiratory
failures resulting from blunt chest trauma
occur within the first few post-injury
hours.113 An elevated alveolar-arterial
gradient or a low PaO2/FiO2 ratio on initial
arterial blood gas should raise suspicion.114 Good pulmonary toilet is important and may be achieved in a variety of
ways which can/should be used in combination. These include nasotracheal suction, chest physiotherapy, postural drainage, and blow bottles are simple yet effective ways to minimize atelectasis and expel bronchial secretions.75
vasoconstriction reduces shunting (ventilation-perfusion mismatch) thereby reducing the degree of hypoxia that would otherwise be present.104-109 In uncomplicated
cases, the pulmonary contusion begins to
resolve within a few days and usually resolves within a week.75, 103, 104
Pulmonary contusion is concomitantly
present in roughly 75 percent of cases of
flail chest injury and when it is present
morbidity and mortality are more than
doubled.82-84 Although not specific, hypoxemia is the most common finding in
pulmonary contusion so when it is present
contusion should be considered in the differential diagnosis.75, 108
Management of Flail Chest
In patients with pulmonary contusion it is
important to avoid over-hydration because, as pointed out earlier, hypervolemia
worsens fluid extravasation into the lungs.
In the absence of shock, fluids should be
given judiciously but under-resuscitation
should also be avoided if the patient is in
shock. Rapid, and overly aggressive, fluid
resuscitation with crystalloids can increase
the volume of the pulmonary contusion
and may even injure adjacent healthy
lung.108, 115, 116 When there is hypovolemia
due to blood loss blood should be given.
In the past colloid preparations have been
suggested as a reasonable fluid choice for
patients with blast lung and pulmonary
contusion however colloids do leak out of
the capillaries and there is no evidence
that outcomes are improved by their use.75,
Because it was previously felt that it was
the movement of the flail segment that
was the primary cause of hypoxia, earlier
treatment focused on reducing the movement of this segment. First aid measures
involved external methods to reduce
movement of the flail segment and inhospital treatment involved “internal stabilization” using endotracheal intubation
with mechanical ventilation and positive
end-expiratory pressure. Experience has
shown, however, that the incidence of
pulmonary infections, the number of days
a patient spends in the intensive care unit,
the duration of hospitalization, and mortality are all reduced when flail chest or multiple rib fractures are managed noninvasively.110-112 Patients with flail chest
should have their ventilatory status frequently assessed, adequate analgesia
should be provided (to include intercostal
nerve blocks), and coughing and deep
breathing should be encouraged. Mechanical ventilation should be reserved for
the patient with severe pulmonary failure
from the underlying lung injury; early intubation is not indicated.
117
The goal of fluid replacement in thoracic
injured casualties should be to restore and
maintain euvolemia. The patient without
extensive multiorgan injury who responds
to aggressive pulmonary toilet fluids can
be managed by monitoring the adequacy
of end organ perfusion using clinical and
laboratory data.75
29
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Clifford C. Cloonan, MD
Breathing
the remainder [7.5%] being caused by
bombs, mines, and grenade fragments.118(p.137) In 837 [92.7%] of the cases,
the penetrating missiles entered the abdomen through the thorax; in the other 66
[7.3%] cases, they entered the abdomen
and then penetrated the diaphragm. In 418
[46.3%] cases, the wounds were on the
right side and in 419 [46.4%] on the left
side; this being a significantly different
distribution of diaphragm injury than that
seen in civilian blunt trauma injury (in
which left side injuries predominate), as
will be discussed later. In 20 [2.2%] cases
both diaphragms were perforated. In the
remaining 46 cases this information was
not documented.
Thoracoabdominal and
Diaphragmatic Injury
Injury to the diaphragm in combat situations is almost always the result of penetrating injury but as previously stated, as
the incidence of penetrating trauma of the
chest has been reduced by the use of body
armor, the proportion [not absolute number] of diaphragmatic injury caused by
blunt trauma will likely be increased. Diaphragmatic injury caused by a penetrating
missile is different from that caused by
blunt injury in terms of mechanism of injury, pathophysiology, and anatomy as
will be discussed later.
The epidemiology of penetrating injury of
the diaphragm in civilian casualties is different from those occurring in combat. A
study by Demetriades119 found that of 163
penetrating injuries of the diaphragm 139
were caused by knife wounds and 24 were
caused by gunshot wounds; only 75% of
these patients had concomitant intraabdominal injury making this group considerably different from combat casualties
with wounds of the diaphragm in whom
some degree of intra-abdominal injury
was almost universal – this no doubt being
due to the predominance of knife wounds
in the civilian series. In this civilian series
early diagnosis and treatment resulted in a
3.2% mortality rate as compared to a late
mortality as high as 30% in some groups;
this finding confirms the importance of
early diagnosis and treatment that was
observed during World War II.
During World War II penetrating injuries
of the diaphragm were categorized under
the more general heading of “Thoracoabdominal Injuries” -- and in virtually every
case, because the term “thoracoabdominal
wound” was reserved for only those chest
and abdominal wounds caused by a single
missile, one did not exist without the
other; although occasionally a missile that
entered the chest could transmit sufficient
force through an intact diaphragm to produce an abdominal injury this was a rare
occurrence.
Between 1943 and 1945 the 2D Auxiliary
Surgical Group treated a total of 903 casualties with thoracoabdominal injury; 247
of these being fatal.34(p.414) During this
same period the 2D Auxiliary Surgical
group treated 1,364 casualties with thoracic injuries so in their experience thoracoabdominal wounds accounted for almost
40% of all wounds of the chest – a surprisingly high percentage that underscores the
importance of looking for this injury in all
casualties with penetrating injuries of the
chest. In this series artillery and mortar
fire caused 590 [65.3%] of these thoracoabdominal wounds, and rifle, machinegun, and pistol fire caused 245 [27.1%];
When considering whether a missile might
have caused a thoracoabdominal wound
both anatomic and physiologic factors
must be considered. Because the plural
reflection generally follows the outline of
the periphery of the ribs and costal cartilages any missile that reasonably could
have passed from one side of this bound-
30
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
cally attributed to “protection” that is afforded by the liver;121 although this has
been disputed 122 (more on this later).
ary to the other should be assumed to have
penetrated the diaphragm. But anatomy is
not the only factor to consider; physiology
also plays a role. The diaphragm is not
simply an immobile structure that forms a
consistent boundary between the chest and
the abdomen; if this were so diagnosis of
thoracoabdominal injury would be much
simpler. The diaphragm is a domed, dynamic organ that moves a considerable
distance during the respiratory cycle; these
factors significantly increase its susceptibility to penetrating injury. In full expiration, any missile entering below the seventh interspace posteriorly or the fourth
rib anteriorly might cause injury to the
diaphragm.118(p.106-108)
In civilian trauma the incidence of diaphragmatic injury is estimated to be 1% to
6% of all patients sustaining multiple
trauma.123-125 Maddox et al. found that rupture of the diaphragm occurs in approximately 5 per cent of cases of severe blunt
trauma to the trunk, and that in this group
the mortality may be as high as 50 per
cent.126
A comprehensive English literature review
of 2288 civilian patients with diaphragmatic injury found that the injury was
caused by penetrating trauma 53% of the
time (of which 55% were knife wounds
and the remainder gunshot wounds) and
blunt, 47% of the time. Eighty-six percent
of the cases of blunt traumatic diaphragmatic rupture occurred during a motor
vehicle accident, 4% were caused by auto
versus pedestrian accidents, and falls,
motorcycle accidents, and crush injuries
each caused 3%.124, 127
The upper limits of the abdomen are
bounded by the diaphragm, which in full
expiration elevates to the level of the nipples anteriorly and the tips of the scapula
posteriorly. These correspond to the level
of the fourth and sixth ribs, respectively.
Because the thoracic cavity extends inferiorly to the costal margins, many intraabdominal organs are within the region of
the lower chest.
Sarna and Kivioja reviewed forty-one
cases of blunt diaphragmatic injury and
found that 71% were caused by motor vehicle accident and 10% by a fall from a
height. The mortality rate in their series
was 12%; with death and most of the
complications being related to associated
injuries and not the result of the diaphragmatic injury; splenic injury being
common.128
The position of the casualty at the time of
wounding must also be considered. Penetrating missiles entering even the uppermost portions of the chest of a prone combatant might well pass through the diaphragm causing thoracoabdominal injury.118(p.102)
Injury to the diaphragm can occur in both
blunt and penetrating thoracoabdominal
wounds. Diaphragmatic rupture is seen in
1% to 3% of patients with blunt chest
trauma.120(p.92) The mortality rate of blunt
diaphragmatic injury is high because when
diaphragmatic rupture is present it is indicative of very severe injury.120 It is generally reported that most diaphragmatic
ruptures occur on the left side (9:1 left
sided predominance);120 this being typi-
Blunt, unlike penetrating, injury to the
diaphragm is caused by creation of a sudden pressure differential between the pleural and peritoneal cavities. This pressure
differential can force organs from one cavity through the diaphragm and into the
other. A common mechanism of blunt
traumatic injury is lateral impact of an
occupant’s chest wall during a motor ve-
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Contrary to most other studies, Waldschmidt et al., from the University of Alabama, in a retrospective study of 86 cases
of diaphragmatic rupture, found no great
predominance of left-sided injury, with
58% being left-sided and 39.5% being
right-sided). Initial mortality in this series
was approximately 16% initially, but it
increased significantly to 53%-66% if diagnosis was delayed and bowel obstruction develops from incarceration of herniated viscera.133
hicle crash. This causes distortion of the
chest wall and tears the ipsilateral diaphragm. Forces applied to the front of the
abdomen, such as might occur from a
high-riding safety belt during a front-on
accident, can create a large radial tear in
the posterolateral aspect of the diaphragm
and can force abdominal contents into the
chest cavity.
Most series of blunt diaphragmatic injury
have demonstrated a predominance of left
sided injury with 65% or more, and in
some series as much as 85%, being leftsided.125, 129-131 Right-sided ruptures, although less common, have more severe
associated injuries and they generally require greater force of impact. The exact
reason for this predominance of left-sided
diaphragmatic injury is unclear but it has
been attributed to “protection” that is afforded to the left diaphragm by the liver.
In Shah et al.’s series of 980 patients with
diaphragmatic rupture there were 1,000
injuries, of which 685 (68.5%) were leftsided, 242 (24.2%) right-sided, 15 (1.5%)
bilateral, and 9 involved pericardial rupture (0.9%); 49 remained unclassified.130
In a series of 20 patients with traumatic
rupture of the diaphragm Anyanwu et al.
found the left hemidiaphragm was ruptured in 85 per cent and the right in 15 per
cent of cases.131 Troop et al. found that
sixty-four percent of the blunt diaphragm
injuries in their series were left sided.125
It has been suggested that ruptures of the
diaphragm actually do occur to both sides
in almost equal frequency but because
those occurring on the right side are generally more lethal, with many dying before
reaching a hospital;122 most hospital-based
series appear to show a predominance of
left-sided injury.120
Physical Examination
Unfortunately field diagnosis of thoracoabdominal injury is problematic and the
best that can be hoped for is to use the
tools of history, signs and symptoms, and
physical examination to raise or lower the
probability of thoracoabdominal injury in
a patient with a penetrating chest
wound.118(p.109) Sukul et al. in their study of
63 patients with traumatic diaphragmatic
injuries found that specific signs or symptoms of diaphragmatic injury were generally absent. Diagnosis prior to operative
intervention was only made in 32% of the
patients and in only one case was it suspected on the basis of physical findings
(peristalsis on chest examination).134
Aronoff et al.132 at the University of
Texas, retrospectively reviewed 161 cases
of diaphragmatic injuries and assessed the
reliability of various diagnostic studies in
diagnosing these injuries. Eighty-nine percent of the diaphragmatic injuries in this
study were the result of penetrating
trauma. In their series the left hemidiaphragm injured 60% of the time and the
right 36%.
Diagnosis of diaphragmatic injury is difficult even for physicians with access to all
the latest diagnostic tools. Diagnosis of
diaphragmatic injury is made preoperatively in only 40-50% of left-sided and 010% of right-sided blunt diaphragmatic
ruptures; perhaps this is another reason
32
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
As previously noted clinical presentation
is not always helpful in making the diagnosis of thoracoabdominal injury because
thoracic wounds not involving the abdomen often cause pain and spasm of the
upper abdomen, and sometimes even abdominal tenderness and rigidity. Olin135
noted that pain in the upper abdomen and
dyspnea, especially in the recumbent position, is suggestive of diaphragmatic rupture. Brewer, in his review of WWII thoracoabdominal wounds,118 does suggest
that when deep abdominal tenderness to
palpation and rebound tenderness are present in a casualty with penetrating thoracic
trauma, abdominal injury is likely also
present because these findings are never
elicited in patients with isolated chest
wounds.
why left sided injuries of the diaphragm
predominate in most series. In 10-50% of
patients, diagnosis is not made in the first
24 hours. In Shah et al.’s review of 980
patients with diaphragmatic rupture the
diagnosis was made preoperatively in
43.5% of cases; in 41.3% it was made at
exploration or at autopsy and in the remaining 14.6% the cases the diagnosis
was delayed. The mortality was 17% in
those in whom acute diagnosis was made,
and the majority of the morbidity in the
group that underwent operation was the
result of pulmonary complications.130
Aronoff et al., in their review of diaphragmatic injury also found physical examination to be generally unreliable. Examination of the abdomen was unremarkable in 44% of the patients with penetrating injuries and in 55% of blunt injuries.
They found physical examination to be
more reliable when the injury involved the
left rather than the right hemidiaphragm.
Decreased breath sounds were documented in 49% of the patients with penetrating trauma and 61% of the patients
with blunt trauma.132
He also noted that while pain in the shoulder is not universally present in patients
with abdominal injury, when it is present
in a casualty with a penetrating chest
wound [one that doesn’t involve the
shoulder], injury to the diaphragm should
be suspected.118(p.109) The presence of nausea and vomiting also suggests the presence of abdominal injury because while
these can sometimes occur in isolated thoracic trauma, they are not common. While
the presence of normal bowel sounds
some time after injury suggests that there
is no hollow viscus injury they say nothing about the possibility of solid organ
injury in the abdomen; in such cases active peristalisis often persists.118(p.109) The
presence of blood in vomitus also suggests
abdominal injury but this is not conclusive
because the blood may have originated in
the lungs. Blood in the urine also raises
the likelihood of concomitant abdominal
injury in the chest wounded casualty.118(p.110) Serial examination is essential
in all patients with chest trauma who
could have injury to the diaphragm and
who do not undergo laparotomy.130
Although physical examination is limited
in its ability to diagnose diaphragmatic
injury this diagnosis is suggested when
auscultation of the chest reveals bowel
sounds in the chest or when there is dullness to percussion.
Because diaphragmatic injury is rarely the
immediate life-threat in multiply injured
patients, the pre-hospital physical examination should, as always, focus the identification and treatment of the more common life threatening problems; specifically it should focus on identification of
injuries, such as tension pneumothorax,
that can be treated in a pre-hospital setting.
33
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Peritoneal Lavage
Ultrasound
Although not a procedure that can, or
should, be performed at, or near, the pointof-wounding, diagnostic peritoneal lavage
(DPL) can help make the diagnosis of thoraco-abdominal injury; and this procedure
should be performed, when indicated, at
the level of the Battalion Aid Station. The
results of the DPL can be used to make
triage and evacuation decisions.
Ultrasound is increasingly being used to
diagnose intra-abdominal injury and it is
particularly effective at picking up intraabdominal bleeding that is associated with
blunt and penetrating solid organ injury.
Diagnostic ultrasound is now sufficiently
durable, lightweight, and easy to use as to
be of use at the level of the battalion aid
station. Ultrasound can generally easily
pick up large holes in the diaphragm or
herniation but it may miss small tears
caused by penetrating injuries.
Although frequently helpful it is important
to note that a DPL can be negative in thoracoabdominal injury, particularly when
there has been a single penetrating injury.
An isolated penetrating chest wound with
diaphragmatic penetration can cause
bleeding into the lesser sac, which may
not communicate with the rest of the peritoneal cavity and would therefore show no
evidence of bleeding after a DPL. Positive
DPL results, as manifested by drainage of
lavage fluid out of the chest tube or
greater than 10,000 RBC/mm3 in the lavage fluid correlate with diaphragmatic injury.
Treatment and Evacuation
Resuscitation of potentially thoracoabdominal-wounded casualties should focus
on rapid stabilization, particularly of the
casualty’s respiratory status, and on rapid
transport to a medical facility capable of
performing resuscitative surgery on these
complicated patients. Death in patients
with diaphragmatic injury is almost always the result of associated injury, most
specifically injuries to the spleen and the
aorta, so these injuries should be the focus
of resuscitative efforts. Mortality in civilian series of patients with diaphgramatic
injury (mostly blunt) ranges from 1525%.120
Aoronoff et al. found that peritoneal lavage, when performed, was falsely negative
in 36% of patients with blunt trauma, in
17% of patients with penetrating trauma,
and in 23% and 18% of right and left
hemidiaphragm injury, respectively. In a
patient with chest tubes in place, several
liters of fluid may be instilled into the abdomen at the time of lavage and chest tube
output monitored to see if this fluid comes
out of the chest.132 Troop et al. suggested
that the diagnosis of thoracoabdominal
injury can be improved by instilling a
small amount of methylene blue into peritoneal lavage fluid to make it easier to see
if this fluid drains out of a chest tube. Methylene blue can also be instilled into the
chest through a chest tube and its presence
sought in peritoneal lavage fluid.125
As in the management of all serious traumatic injuries, a focus on the ABCs is the
cornerstone for prehospital management
of patients with diaphragmatic injury. As
noted earlier, diagnosis of diaphragmatic
injury is difficult even for specialists who
have all diagnostic tools available, so it
should not be surprising that the diagnosis
rarely is made in the field. Fortunately,
failing to diagnose this injury in the field
is unlikely to have adverse clinical consequences because no specific prehospital
treatment is required for this injury. The
key to improved outcomes in patients with
diaphragmatic injury is maintenance of the
34
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
tion after cardio-respiratory abnormalities
had been corrected and shock controlled.
This is not the case in casualties with thoracoabdominal wounds; in such patients
the time to operation is of great importance. These patients must be resuscitated
as rapidly as possible and they should be
operated on as soon as they appear able to
tolerate surgery.118(p.112) Indeed, in those
patients with suspected thoracoabdominal
injury who persist in shock despite initial
resuscitative efforts, immediate surgery is
the resuscitation method of choice.118(p.122)
In the majority the most lethal part of the
thoraco-abdominal wound was the abdominal component.
airway and ventilation and appropriate
treatment of associated injuries.
Fluid resuscitation should be initiated in
the field but should not be overly aggressive; it should be focused primarily on
maintaining cerebral perfusion as defined
by a normal mental status. Excessive fluid
resuscitation both aggravates blood loss
and increases the risk of ARDS. When
serious and persisting shock is present,
blood, whole blood if available, should be
administered as soon possible. In the thoracoabdominal-wounded casualty it is especially important to rapidly restore as
near normal a respiratory status and oxygenation as possible. The casualty should
be positioned for optimal ventilation,
sucking chest wounds should be closed by
occlusive
dressing,
pneumothoraces
should be alleviated by tube thoracostomy
by a qualified healthcare provider as soon
as practicable, and, if available, oxygen
should be administered. Tube thoracostomy should be done with special caution in any patient with suspected diaphragmatic injury because of the risk of
injury to herniated abdominal contents
within the pleural cavity. Pain should be
alleviated by adequate doses of analgesia
(morphine) and/or intercostal nerve
block.118(p.112) A nasogastric tube should be
inserted and connected to low intermittent
suction as soon as this is available and
possible. Early antibiotic administration
with an antibiotic that will provide adequate coverage for enteric bacteria is indicated for all patients with potential penetrating thoracoabdominal injury.
Penetrating Chest Trauma
Penetrating chest trauma is the predominate form of chest injury in combat casualties. Signs and symptoms in patients
with penetrating chest trauma may range
from minor, even initially unrecognized
by the casualty, to grossly apparent and
life threatening. Casualties with penetrating chest trauma tend to divide themselves
rapidly into one of three categories:
1) Those who die within less then 30
minutes
2) Those who can be managed solely
by insertion of a chest tube and,
by far the smallest group
3) Those who require thoracotomy.
Very few of the first group can be saved
even if injured in immediate proximity to
a Level I trauma center equivalent facility
and in most instances the last group only
becomes apparent when there is persistent
and significant bleeding from a chest tube.
From the standpoint of isolated thoracic
injury, within reason the length of time
required to restore a thoracic-wounded
casualty to near his normal physiologic
status before operation is not critical. It
was observed during WWII that most
casualties with isolated chest wounds
benefited from a short period of stabiliza-
Insertion of a chest tube for management
of penetrating chest trauma in combat
casualties is not new. As long ago as the
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
toms.7(p.152) Jolly did, however, go on to
note that, “[I]t is the small wound of the
chest caused by a tangential bullet or shell
fragment, with rupture of the intercostal
vessels, which is important and seen most
frequently. Until at least 48 hours have
passed, no such wound may be regarded
as comparatively unimportant; at any time
within this period it may give rise to a full
haemothorax.”7(p.154)
American Civil War, surgeons treated intrathoracic collections of fluid in the pleural space by placement of a trocar into the
chest. The Confederate Surgeon, J.J. Chisolm, described the indications and procedure for chest tube insertion as follows:
“The evil which the surgeon fears from
perforating wounds [of the chest]…is
that…a[n] effusion may rapidly accumulate
in
the
thoracic
cavity…Respiration becomes much embarrassed with marked dyspnoea. Percussing the side, will now give a dull,
heavy sound, instead of the ordinary
clear, sonorous one of health…When the
surgeon has recognized such collections
as rapidly forming in the chest after
gunshot wounds…an early evacuation
will be required…an opening for the escape of the fluid should be made at the
point which nature indicates, but, in
cases of excessive effusion, any broad
intercostal space, between the sixth and
eighth ribs of the right, or between the
seventh and ninth on the left, might be
the point selected…a trocar and canula,
should be introduced at right angles to
the chest and near the upper edge of the
rib, towards its angle, in a line continuous with the posterior border of the
armpit.1(p.279)
Jolly also noted that in the Spanish Civil
War roughly half of all combat caused
chest wounds do not require operation in
the forward area. He went on to say that
when there has been a through-andthrough bullet wound with no injury to the
intercostal vessels the casualty usually
does fine with rest and morphine for pain.
Although about 90% of surviving casualties with penetrating chest wounds have
hemoptysis, in casualties with gunshot
wounds of the chest bleeding generally
decreases rapidly and stops within a week.
Jolly stated that it is better not to attempt
removal even if a bullet is retained in the
lung as long as there is no extensive bleeding.
Not all of Jolly’s recommendations have
stood the test of time. Prior to and even
during the early years of World War II it
was sometimes suggested that a thoracotomy for persistent intrathoracic bleeding might be avoided by withdrawing
blood from the chest via a chest tube and
then replacing this blood with air under
pressure. The thought was that the increased air pressure in the pleural space
would decrease the rate of bleeding by
decreasing the pressure differential between the bleeding vessel(s) and the pleural space.7(p.162) While conceptually sound,
practically, the risks (primarily tension
pneumothorax) outweighed any potential
benefit because the reduction in blood
flow gained by this procedure is minimal.
Not surprisingly missiles that strike the
chest and cause injury to the heart or great
vessels have a high mortality. Contrarily,
missiles, even high velocity missiles, that
strike only lung, often cause surprisingly
little serious injury. This fact, that the lung
is more tolerant of wounding by high velocity bullets than other tissues, has been
known for some time.136(p.179) In 1939,
commenting on chest wounds in the Spanish Civil War, Jolly noted that, “Bullet
wounds passing cleanly through the parenchyma of the lung cause little haemorrhage and, when the initial shock of injury
has passed, remarkably few symp-
36
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
80 to 85%, can be effectively managed
solely by insertion of a chest tube. Current
indications for thoracotomy, as promulgated in the Advanced Trauma Life Support Course,51 are persistent hypotension
despite aggressive fluid replacement, initial output of greater than or equal to 1500
mL of blood upon chest tube insertion,
continued bleeding from chest tube greater
than 200 mL/h for 2 - 4 hours, and/or need
for persistent blood transfusion. Other authors have suggested similar guidelines
but include as well massive continuing
hemorrhage greater than 2000 mL and
hemothorax in the presence of a widened
mediastinum.94, 138(p.481) It should be noted,
however, that not all trauma surgeons
agree with the concept of using the initial
blood loss from a chest tube, as described
above, as the prime indicator of need for
thoracotomy.
Hemo- and Pneumothorax
Hemothorax, pneumothorax, and hemopneumothorax are common complications
of penetrating chest trauma. In penetrating
chest injury almost always both blood and
air accumulate to some degree within the
pleural space. Hemothorax alone can
cause hypotension and cardiopulmonary
dysfunction both through hypovolemia
and by compressing the lung and reducing
venous return. Because the pleural space
may accommodate 30% to 40% of the
blood volume, the most common clinical
presentation is hypovolemia.94(p.481) Depending upon the extent of bleeding, and
the presence or absence of concomitant
pathophysiology, the clinical status of a
patient with hemothorax can range from
stable to moribund. When massive,
hemothorax may be difficult to differentiate from tension pneumothorax because
both can present with diminished breath
sounds, hypotension, tracheal deviation,
and cardiovascular collapse. The only distinctions being that in massive hemothorax the neck veins are collapsed instead of
distended and the affected side of the
chest is dull to percussion instead of tympanic – but these findings are not invariably present even in tension pneumothorax
so distinguishing between these two can
be difficult in the field.
Mattox et al.139 (pp.345-353) believe that initial
chest tube output alone is not as important
as the rate of ongoing hemorrhage. They
point out that while initially there may be
up to 1500 ml of blood loss through a
chest tube, if there is no further bleeding,
such casualties can often be managed nonoperatively. Demetriades et al. conducted
a prospective study of 543 patients with
stab wounds of the chest.140 They found
that the best indicators of the need for
early thoracotomy were the presence of
signs of cardiac or major vascular injury;
e.g. tamponade, profuse bleeding, an absent or diminished peripheral pulse, and
persisting shock. They suggested that the
initial chest tube output, and even the rate
of blood loss from the thoracotomy tube,
were not reliable indicators of the need for
thoracotomy; they recommended that
these criteria not be used as the sole indicators for thoracotomy. They even found
that some patients initially in shock could
be managed non-operatively, as could
even most patients with massive air leaks.
Because hypotension and exsanguination
are the primary concern in casualties with
a significant hemothorax treatment of this
condition should focus on hemorrhage
control and restoration of volume. Partial
control of hemorrhage can be achieved by
re-expansion of the lung with insertion of
a chest tube but severe hemorrhage requires surgical control. As noted earlier in
the “Circulation” section when hemorrhage is internal and uncontrollable aggressive volume resuscitation is not recommended.137 As previously stated the
majority of cases of hemothorax, roughly
37
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
It is worth noting, however, that the Demetriaes’ series was a civilian series of
stab wound patients and results from this
series might well not apply to a population
of combat casualties with penetrating
fragment or bullet wounds to the chest. In
a combat zone where there is often inadequate manpower, multiple casualties to
attend to, and frequently less than sophisticated diagnostic tools available, a more
aggressive surgical policy is likely to produce more favorable results. However, in
the event that surgery cannot be performed
for some reason, it is useful to know that
many patients with combat-associated
penetrating chest trauma who survive to
reach medical care, even those with significant and sustained blood loss, will
likely do well without formal surgical intervention. Finally it should again be
pointed out that while combat casualties
with penetrating cardiovascular injury
who survive long enough to reach medical
care often have serious injury, it is quite
often those with injuries to intercostal vessels that bleed the most and the longest.
A pneumothorax may be open and “sucking” with exchange of air during respiration through the chest wall defect, it may
be closed, or it may be open or closed at
various times. A small portion of casualties with a closed pneumothorax go on to
develop a tension pneumothorax when air,
which enters the pleural cavity during inspiration, can’t leave during expiration.
This condition is discussed in detail later.
During World War II it was noted that all
penetrating chest wounds had the potential
to be “sucking” and this observation influenced the treatment recommendations for
such wounds (see below). It was noted
that a sucking wound sometimes sucked
(or blew) constantly and sometimes only
when the skin and muscles planes were in
a certain alignment. Anatomy at the point
of wounding frequently determined
whether or not a wound sucked. It was
noted that although generally a large
wound is more likely to suck than a small
wound, size is not necessarily the determining factor. A relatively small wound in
the anterior chest wall, 2 centimeters or
less in diameter, might suck constantly
because in this area the muscles are thin
and the rib interspaces are wide, but a larger posterior wound, through the heavy
muscles of the back, might not suck at
all.142(p.5)
In any case, in the pre hospital environment, all casualties with penetrating chest
trauma who meet the ATLS criteria for
thoracotomy (as defined above) should be
evacuated in the “Urgent” category to a
facility with a surgeon capable of performing resuscitative cardiothoracic surgery.141(p.107)
In many instances casualties with a “sucking” chest wound can tolerate the injury if
the amount of air entering the wound from
outside is not greater than the difference
between the tidal volume (resting tidal
volume in adult males is approximately
500 cubic centimeters) and the original
vital capacity (which is approximately
4800 cubic centimeters in the average
adult male). As Brewer and Burford note,
without treatment, the outcome of a casualty with a “sucking” chest wound is determined by the size of the wound and the
original vital capacity.142(p.5) If the size of
Pneumothorax may occur with either blunt
or penetrating trauma. In combat settings
the great majority are caused by penetrating injury. Blunt trauma can cause a
pneumothorax by a variety of mechanisms; a sharp rib fracture can puncture a
lung, air can leak into the pleural space
following a tracheobronchial injury, and
alveoli may burst following blast injury or
other rapid compression of the chest
wall.67
38
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
involved side (3) jugular venous distension and (4) tracheal deviation to the contralateral side. A tension pneumothorax is
associated with a marked decrease in pulmonary compliance, increased peak airway pressures, hypoxemia, and hypotension that eventually leads to cardiovascular collapse. Tracheal deviation, while
considered a cardinal sign of tension
pneumothorax, is inconsistently present
and chest wall movement and breath
sounds are generally diminished or absent
on the affected side in both pneumothorax
and tension pneumothorax.67
the traumatic opening is less than the size
of the glottis, which is about 2 centimeters
in diameter in the average adult male, an
adequate amount of air can usually enter
through the glottis to meet physiologic
requirements. If the opening in the chest
wall is larger and the amount of air entering the chest through the open wound during each inspiration is great enough to interfere with the tidal air requirement intake, asphyxiation is possible.142(p.8)
As previously noted, early in World
War II aidmen were instructed to cover
only “sucking” wounds with an occlusive dressing. Later in the war instruction was given that all chest wounds
were to be treated in this manner because a penetrating chest wound that
did not suck at one time, or in one position, might suck in another. On the
battlefield the recommendation was
that any type of dressing that was
available could be used, even a piece
of clothing.
Tension Pneumothorax
One cause of breathing difficulties in battlefield casualties is a tension pneumothorax -- a closed accumulation of air in the
pleural space into which there is an opening surrounded by tissue that allows air to
enter but not to escape. Tension pneumothorax has been clinically defined as
“The progressive accumulation of air under pressure within the pleural cavity, with
shift of the mediastinum to the opposite
hemithorax and compression of the contralateral lung and great vessels…”.35(p.388)
As recently described by Domino, tension
pneumothorax is a clinical, not an anatomic, diagnosis. Diagnosis is based upon
the presence of a pneumothorax and a
combination of some or all of the following clinical findings, (1) worsening hypotension (2) tympany on percussion of
Tension Pneumothorax
One of the most common causes of tension pneumothorax during peacetime is
the use of high ventilator pressures in patients with restrictive lung disease. On the
battlefield tension pneumothorax is almost
always caused by penetrating trauma.
While pneumothorax is quite common in
combat casualties with chest injury, tension pneumothorax is very uncommon,
particularly among those who survive long
enough to be treated. Unfortunately, good
data on the true incidence of tension
pneumothorax in combat casualties is
lacking. The reason for this is, as Bellamy,
McPherson, and Feigin have stated, ten-
39
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
explained as being likely due to the following:
sion pneumothorax leaves little persisting
physical evidence, even in the dead, and it
is reversible when properly treated, having
“a willow-of-the-wisp quality.” Diagnosis
of tension pneumothorax in the field is
difficult because clinical findings such as
respiratory and circulatory collapse are
nonspecific.143
1) The preponderance of shellfragment wounds, which resulted
in a preponderance of large defects of the chest wall. For physical reasons, air could not be entrapped in the chest in such
wounds. [NOTE – If true this
could also explain the predominance of bullet-caused tension
pneumothoraces seen in the
Bellamy study. Now that improved conventional munitions,
with their very small fragments,
have almost completed replaced
unimproved munitions it is
unlikely that this explanation
would be valid today].
2) The routine application of occlusive dressings tightly enough to
end the sucking or blowing effect
of the open chest wound but not
so tightly that a tension pneumothorax was built up.
3) The almost routine use of a flapper-valve decompressive catheter
in collecting stations or battalion
aid stations.
4) The excellent screening of inductees in World War II, as a result of
which preexistent restricting pleural adhesions, which were rather
frequent in World War I soldiers,
were extremely uncommon [it is
unclear how standard medial
screening of inductees would have
picked up this condition]
Bellamy and colleagues used autopsy
chest radiographs from the Vietnam era
Wound Data Munitions Effectiveness
Team (WDMET) files to estimate the
prevalence of tension pneumothorax in
combat casualties. Somewhat surprisingly,
in this review they found that eighty percent of the wounds were created by military small arms (an unexpectedly low percent of fragment-caused injury) and all
were to the periphery of the lung and not
the hilum (injuries of the hilum often being quickly lethal). If Bellamy et al. were
able to correctly identify, from postmortem chest radiographs (the authors
themselves state that “using post-mortem
chest radiographs for diagnostic purposes
is fraught with the possibility of errors…”), those dying from a tension
pneumothorax, then according to this
study, 3%-4% of fatally wounded casualties (not all casualties) recorded in the
WDMET database died from a tension
pneumothorax.
During World War II traumatic tension
pneumothorax was rarely seen in forward
hospitals, although it was somewhat more
common as a postoperative or posttherapeutic complication. Its infrequency is
evident in the statistics of the 2d Auxiliary
Surgical Group. Tension pneumothorax
was encountered by the 2nd Auxiliary
Group only 11 times in its treatment of
2,267 thoracic and thoracoabdominal injuries (0.9%).144 (p.148)
It was felt that the majority of tension
pneumothoraces observed during World
War II were the result of continued leakage of air from lacerated pulmonary parenchyma combined with closure of the
external chest wound which converted an
open pneumothorax into a tension pneumothorax.144(p.149)
This infrequency of observed tension
pneumothorax during World War II was
40
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Breathing
Despite representing only a relatively
small percentage of all medical conditions
present in combat casualties a tension
pneumothorax is very important to recognize because it is one of the few, potentially fatal, combat-caused medical problems that can be treated, at least temporarily, with minimal training and equipment.
While treating a tension pneumothorax is
no guarantee of ultimate survival, rapid,
and appropriately performed needle thoracentesis, may allow many with this condition to live long enough to reach more
definitive care.
may be exceedingly difficult to appreciate
on the battlefield.149
The practical consequence of these facts is
that if the benefits of treatment are to be
realized in combat casualties, rapid diagnosis must be made, and treatment rendered, at, or near, the point of wounding,
by one of the least trained members of the
health care team -- the combat medic. This
means that the threshold for treatment
must be low or this potentially treatable
condition will go untreated until too late.
Bellamy et al. have suggested that because
of the difficulties in diagnosing tension
pneumothorax in the field and because, if
it is to be of use at all, needle thoracentesis
must be done quickly by medical personnel nearest the point of wounding. According to Bellamy medics should be
taught to do this procedure in every decompensating casualty with an apparently
penetrating chest injury who does not also
have a serious head injury. In some civilian settings paramedics are authorized to
perform needle thoracentesis150, 151 so it
would seem that this procedure is reasonably within the capabilities of combat
medics and corpsmen.
Thus this small group of combat casualties
represents a significant subset of combat
casualties sustaining an injury which
while rapidly fatal if untreated, could be
readily treated at, or near, the point-ofwounding. When compared to an estimated 20% of combat casualties who die
from treatable blood loss,145-147 and to the
less than 1% who die from airway obstruction,148 perhaps as much as a third of
all potentially life saving first aid for
combat casualties could be realized by
effective emergency treatment of tension
pneumothorax.143 It is for this reason that
early diagnosis and effective treatment of
tension pneumothorax is so important.
Unfortunately tension pneumothorax often
causes death before treatment can be rendered and, as noted earlier, it is difficult to
correctly diagnose in the field since most
of its signs and symptoms are not specific.
Therefore a presumptive diagnosis of tension pneumothorax should be made in
every casualty with a penetrating chest
injury and significant respiratory distress,
particularly if there is also hypotension.
Battlefield diagnosis of tension pneumothorax should not be based upon the
presence of the classically described findings of decreased breath sounds, tracheal
deviation, and hyperresonance to percussion, because these signs may not always
be present.149 Even if present these signs
Needle Thoracentesis
Almost all casualties with penetrating
chest trauma have some degree of
hemo/pneumothorax and it is unlikely that
the additional trauma caused by a needle
41
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Clifford C. Cloonan, MD
Breathing
stances needle thoracentesis is sufficient.
Finally, there is currently no data showing
benefit from point-of-wounding tube thoracostomy when performed by civilian
paramedics,150, 151 and certainly none demonstrating its efficacy in a combat setting,
performed by corpsmen or medics. This
does not mean, however, that there is no
benefit, just that there is no proof of benefit at this time.
thoracostomy would significantly worsen
their condition should they not actually
have a tension pneumothorax.151 The effect, however, of a low treatment threshold for tension pneumothorax would be
that many casualties without this condition
would also be treated, exposing them to
the risks of treatment (principally creation
of a pneumothorax in a casualty who does
not already have one, and less often,
hemothorax), without hope of benefit.
Holcomb et al. have shown that needle
thoracentesis with a 14-gauge needle rapidly relieves elevated intrapleural pressure
in a swine model of traumatic tension
pneumothorax.153
Holcomb’s
study
showed that the therapeutic effect of needle thoracentesis was sustained for 4 hours
and throughout this period it was equivalent, in its ability to relieve tension, to tube
thoracostomy with a 32F chest tube.153
Minimal equipment requirement, ease and
speed of performance, and low likelihood
of serious complications makes needle
thoracentesis the procedure of choice to
relieve tension pneumothorax on the battlefield. Unfortunately, as noted above,
there is no data to show that the apparent
benefits of this procedure outweigh its
cumulative risks. The risks, which include
hemorrhage and creation of a pneumothorax, while generally of little-to-no consequence in the majority of combat casualties, may be of significance in those whose
physiologic state is already precarious
from blood loss and hypoxia. Thus, while
training combat medics and corpsmen to
perform needle thoracentesis seems reasonable an effort should be made to collect data to show that overall benefits exceed risks.
A recent civilian observational study by
Cullinane et al. found that only one of the
19 trauma patients in their study who had
a needle thoracentesis performed received
any significant benefit from the procedure
and whether even this patient would have
had significant problems without the needle decompression is unclear.152 It is important to note however that only five of
these nineteen patients had sustained
penetrating injury making this a very different group of patients than generally
seen in combat.
Chest Tube
Definitive treatment for both pneumothorax and tension pneumothorax involves
insertion of a chest tube through the fourth
or fifth intercostal space, anterior axillary
line – a procedure that most combat medics, and civilian paramedics, are not
trained to perform. In any case tube thoracostomy is not needed for initial treatment
of a tension pneumothorax – in most in-
In performance of needle thoracentesis
cannula length is an important consideration. 149, 154-157 The pectoral muscles,
which can be very thick in young solders,
must be penetrated in order to effectively
treat a tension pneumothorax so the
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Clifford C. Cloonan, MD
Breathing
cathter used must be sufficiently long.
While difficult to appreciate in a combat
situation, if there is no rush of air when
the needle is inserted, it must be assumed
that either the needle was too short, or that
the casualty did not have a tension pneumothorax. Ranger medics currently use
10ga 3-inch needle/catheters for this procedure. (Personal communication – SFC
Rob Miller, Senior Army Ranger Medic)
Blast Lung
Although primary blast injury generally
accounts for less than 3% of all combat
casualties, it is essential that forward
medical care providers recognize, and appropriately treat and evacuate, combat
casualties with this injury. Patients exposed to underwater blast or to explosions
in enclosed spaces are at much higher risk
than other casualties of sustaining primary
blast injury.162 Troops exposed to blast
enhanced weapons (truck/car bombs, improvised-explosive-devices (IEDs), fuelair explosives, thermobaric weapons etc.)
are also more likely to sustain primary
blast injury. Primary blast injury is difficult to identify even for experienced
medical personnel because there may be
no external evidence of injury and, at least
initially, such patients may appear relatively unharmed. Patients suspected of
sustaining blast lung injury should not, if
at all possible, be allowed to assist in their
own evacuation because any exertion by
such patients significantly increases the
probability of death. Additionally, while
supplemental oxygen is of little value to
most combat casualties, patients with blast
lung (or any cause of pulmonary contusion) often need oxygen to survive.
Casualties on whom a needle thoracentesis
has been performed must be continually
re-assessed because catheters used for this
purpose can easily become occluded by
blood clots and kinking.50(p.8) If an Asherman Chest Seal is available one could be
placed over the needle to stabilize it and
help prevent dislodgement as described by
Allison et al.158
Injury to Trachea and Mainstem
Bronchus
Injuries to the trachea and mainstem bronchus are extremely serious but fortunately
rare. They are most often the result of
penetrating lung injuries, but also occur in
1% to 3% of patients with severe blunt
lung trauma.159 In civilian series the mortality of civilian trauma patients with a
tracheal injury is 30%, half of whom die
within the first hour.91, 94 Traumatic rupture of the bronchus is also rare with a
similarly high case fatality rate. In Bertelsen and Howitz's study, approximately 3%
of 1128 patients at autopsy had evidence
of tracheobronchial injury, with most
(81%) having died before reaching a hospital.160 In civilian series penetrating injuries to the bronchus are rarely seen in the
emergency department both because of the
overall rarity of penetrating chest injury in
this series and because most with this injury die quickly from associated great vessel injury. Charity Hospital in New Orleans reported only 22 cases in a 20-year
period.161
Chest x-ray showing small fragment wounds and primary
blast injury of the lung resulting in pulmonary contusions
demonstrated as infiltrates under the left chest wall.
From the Textbook of Military Medicine, part I, volume 5,
page 302, figure 9-2.
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Clifford C. Cloonan, MD
Breathing
During World War II much of the British
experience with blast injury was gained
through German bombings of Britain. The
relative frequency of primary blast injury
among civilian casualties of these bombings for a time misled U.S. Army medical
officers into believing that blast injury
would be a common occurrence in combat; it was not. Blunt injuries of the intact
chest, with resulting contusion, were frequent, but blast injuries were uncommon
in combat casualties during World War II.
Early in this war these two conditions
were frequently confused.142 (p.32)
Circumferential Burns of the Chest
Wall
Because of the increased military use of
vehicles powered by hydrocarbon fuels
these flammable propellants have increased the risk of burn injury during both
combat and non-combat operations. The
widespread use of vehicle born improvised explosive devices by enemy combatants during operation Iraqi Freedom
has been a major source of combat-related
burn injuries. Combustion of these fuels
can cause problems with ventilation and
respiration in several different ways:
Capt. William W. Tribby, MC163 in his
study of 1,000 battlefield deaths of U.S.
Army troops in Italy, found 13 bodies in
which there were no penetrating injuries
and in which the cause of death was presumably blast injury; several other casualties might also have died of blast injuries,
for while penetrating wounds were present, they were not sufficient in any instance, to account for the fatality.142(p.32)
Nonetheless it was clear to Tribby that
primary blast injury was an uncommon
cause of death in WWII combat casualties.
•
•
•
•
Data prepared by the Medical Statistics
Division, Office of the Surgeon General,
Department of the Army, show 1,021 blast
injuries of non-battle origin in the U.S.
Army for period 1942-45, of which 48
were fatal. For the same period, there were
13,200 battle-incurred blast injuries, 140
being fatal. Of the 6,284 blast injuries occurring in 1944, 76 were fatal; 493 involved the chest, and 25 of these were fatal. The WWII naval experience with blast
injury was considerably more extensive
than that of the Army this no doubt being
due to the fact that the principal munitions
used in naval combat are large high explosive shells intended to destroy ships not
people.
Inhalational burn injury which
usually causes upper airway problems can also cause problems with
ventilation and respiration
Consumption and displacement of
oxygen producing hypoxemic hypoxia
Generation of carbon monoxide
resulting in carboxyhemoglobin
Mechanical interference of respiration by circumferential burn injury of the chest wall.
Although rare circumferential burn injury
of the chest wall can cause restriction of
ventilation that may critically impair the
ability of a seriously burned casualty to
adequately ventilate. When circumferential burn injury impairs breathing it is vital
that this condition be quickly diagnosed
and properly treated. Circumferential fullthickness burn injury of the chest can restrict the bellows movement of the chest
resulting in a reduced tidal volume. This
reduced tidal volume, particularly when
combined with the frequently concomitant
inhalational injury and occasionally present histiocytic hypoxia of carbon monoxide and/or cyanide intoxication, can be
lethal. When this rare injury occurs treatment involves performance of an escharotomy to release the chest wall permitting
44
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Clifford C. Cloonan, MD
Breathing
tic abilities allow this diagnosis to be definitively made in living casualties although the long air evacuation of freshly
wounded casualties may also contribute.
expansion of the lungs. While this procedure is not one that would be done by
most pre-hospital providers, it can and, in
some instances should, be done in the field
by someone properly trained to diagnose
and treat this condition.
Pulmonary embolus diagnosis and treatment is not a subject that is generally addressed in combat casualty care but, as
made clear by the recent high profile death
of embedded NBC journalist David Blood
during Operation Iraqi Freedom,166 this
condition can and does occur and it can
present as a problem in the pre-hospital
environment. The conditions that predisposed David Bloom to this condition were
not unique to him; prolonged immobility
in cramped quarters167, 168 and relatively
older age; dehydration with increased
blood viscosity may have also had a role.
As noted elsewhere in this chapter, demographics indicate that the average age of
combatants from most first-world countries is increasing and, as also noted, long
transport over great distances by motorized transport is becoming increasingly
common. It is also important to note that
there are an increasing number of women
combatants, some of whom will be using
oral contraceptives, and this population is
at increased risk of pulmonary embolus.
Triage and Evacuation of Casualties
with Oxygenation and Ventilation
Problems
While some problems of oxygenation and
ventilation can be definitively addressed
at, or near, the point of wounding, most
require evacuation to a higher level of
care. Dr. Jolly noted in his book, Field
Surgery in Total War, on management of
combat casualties in the Spanish Civil
War, that “As a general rule the only chest
cases allotted to No. 1 Hospitals (the most
far forward field hospital) should be those
in a grave state of shock, especially those
in which there is an open blowing pneumothorax. The majority should be taken
to a No. 2 Hospital (where better care
could be provided).7(p.150)
Pulmonary Embolus
Although pulmonary embolus (PE) does
not appear to be a common cause of respiratory difficulty in combatants its frequency is unknown and it is likely considerably higher than reported because of the
difficulty in making this diagnosis, particularly in the forward areas. Recent data
on the frequency of pulmonary embolus in
combat casualties returning to CONUS
from Iraq and Afghanistan confirm that
pulmonary embolus is a problem in combat casualties.68, 164-166 Despite this apparent increase in PE incidence over previous
conflicts which has been ascribed to there
being a higher percentage of severely
mangled limbs in current operations164 the
most likely reason is that current diagnos-
While little can be done, in the prehospital environment, for the patient with
a pulmonary embolus it is important that
pre-hospital providers be aware of this
condition. They must also be able to recognize which patients are more likely to
have a PE based on risk factors and clinical presentation and they should know
how to provide appropriate initial treatment (apply oxygen if available and perhaps give aspirin) and make appropriate
triage and evacuation decisions for patients with this condition.
In civilian settings pulmonary embolus is
a common cause of death, being the third
leading cause of cardiovascular death in
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Clifford C. Cloonan, MD
Breathing
North America.169 Pulmonary embolus is
an important diagnosis to make early because undiagnosed pulmonary embolism
has a hospital mortality rate as high as
30%; but if properly diagnosed and treated
mortality falls to near 8% and in ambulatory patients to less than 2%.170-175 Unfortunately the diagnosis of pulmonary embolism is very difficult even for experienced clinicians with access to sophisticated diagnostic tools. Less than 35% of
patients suspected by physicians of having
pulmonary embolism actually have this
condition.176-178
Other PE risk factors not likely to be relevant in a combatant include active cancer
and major surgery within past 4 weeks.
Race may also play a role in predisposing
to DVT and PE. Specifically it has been
found that venous thromboembolism and
pulmonary embolism are much less common among Asians and Pacific Islanders
in the United States than in whites and
African Americans.179
Physical examination findings that should
suggest a diagnosis of thromboembolism
include the following:
1) Localized tenderness along deep
venous distribution
2) Evidence of thigh and calf swelling – specifically is there greater
than 3 cm of swelling on the
symptomatic side than on the asymptomatic side when measured
10 cm below the tibial tuberosity?
3) Dilated superficial veins (not
variscose) in the symptomatic leg
4) Pitting edema only in the symptomatic leg
5) Erythema of the symptomatic
leg180, 181
6) Homan’s sign (pain in the calf on
passive dorsiflexion of the foot)
7) Edema, generalized tenderness,
and warmth, may also be present
but these have a low predictive
value because they commonly occur in other conditions that are
much more common in combatants such as musculoskeletal injury and cellulitis.
Although most cases of deep vein thrombosis [DVT] originate in the calf it is rare
for thrombosis in the calf to lead to clinically significant pulmonary emboli; however, one-quarter of calf DVTs do extend
proximally and thrombosis in large
proximal veins is where most clinically
significant pulmonary emboli originate.
Therefore, early recognition and appropriate treatment of calf DVTs will prevent
many cases of clinically significant pulmonary emboli.
Combatants in whom DVT should be considered are those who present for medical
care with complaints of pain, swelling,
and discoloration in a lower extremity. In
this group the following history should be
elicited to assess the likelihood of DVT:
1) History of recent prolonged immobilization – immobilization of
lower extremity in plaster or bedridden greater than 3 days
2) History of recent lower extremity
trauma
3) History of smoking
4) Strong family history of DVTs
5) Recent hospitalization within past
6 months
6) Use of oral contraceptives by
women combatants
Although most combatants with many, if
not most, of these clinical findings will not
have deep vein thrombosis any combatant
with two or more of these findings in
whom an alternate diagnosis is not considered likely should be assumed to have a
DVT until proven otherwise. It is important to recognize and properly treat com-
46
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Clifford C. Cloonan, MD
Breathing
define a pulmonary infarction syndrome in
which patients present with pleuritic chest
pain and/or hemoptysis; a syndrome of
isolated dyspnea; and a syndrome of circulatory collapse.186 They found that among
patients with the pulmonary infarction
syndrome, 14 of 119 (12%) had neither
dyspnea nor tachypnea. Some patients
with circulatory collapse did not have
dyspnea, tachypnea, or pleuritic pain. Patients with the pulmonary infarction syndrome are more likely to have a PaO2 >80
mm Hg [27 of 99 (27%)], than patients
with the isolated dyspnea syndrome, 2 of
19 (11%).
batants with symptomatic DVT because
without treatment about one-half them
will have recurrent venous thromboembolism within 3 months.182, 183 A relatively
high proportion of patients with recurrent
episodes of venous thromboembolism end
up having pulmonary emboli that are fatal
(case-fatality rate over 2-fold higher).184,
185
Pulmonary emboli, when they do occur,
cause ventilation-perfusion defects in
which portions of the lung are ventilated
but not perfused. When there is a moderately large pulmonary embolus the PaO2
drops; the PaCO2 also drops due to hyperventilation but the decrease is not as great
as would otherwise occur because dead
space is increased; pH increases secondary
to hyperventilation but may not increase
as much as expected because there is a
concomitant lactic acidosis caused by decreased perfusion; mixed venous PO2 falls
as a result of an increase in the metabolic
rate and due to decreased perfusion to
some cells and because the hyperventilation-induced alkalosis reduces the amount
of oxygen that can be extracted at the cellular level; increased blood flow through
areas of the lung that naturally have a low
VA/Q also contributes to hypoxia and finally; associated atelectasis does produce
intrapulmonary shunts (V/Q mismatch) in
which portions of the lung are perfused
but not ventilated which worsens hypoxia.
Although pulmonary emboli do produce
increased dead space and cause some diffusion impairment neither of these contribute much to the hypoxia that is associated with pulmonary emboli.
Pleuritic chest pain arises from pleural
irritation caused by a pulmonary infarct;
but pulmonary infarctions are uncommon
in patients without prior cardiopulmonary
disease. Patients with pulmonary emboli
who have comorbid conditions tend to
present with pleuritic chest pain more often than their healthier counterparts.187
Hemoptysis occurs in only 34% of patients with pulmonary embol;.188 and a full
twelve percent of patients with pulmonary
infarction syndrome, have neither dyspnea
nor tachypnea.186
In patients with isolated dyspnea, the degree of dyspnea depends on the degree of
pulmonary vascular obstruction and the
patient's cardiopulmonary reserve – combat troops tend to be cardiovascularly fit
so they would likely be less dyspneic. Patients with less than 50% of their pulmonary vasculature obstructed by clot are
often asymptomatic.187 The syndrome of
circulatory collapse can present as transient syncope, hemodynamic instability, or
frank cardiac arrest. Between 8 and 14%
of patients with pulmonary emboli present
with syncope.189 Persisting right ventricular dysfunction after a large pulmonary
embolus results in hemodynamic instability and severe cases present in cardiac arrest. Kurkciyan et al. have estimated that
Patients with pulmonary emboli present
with a variety of signs and symptoms –
classically they complain of chest pain and
shortness of breath but the “classical”
presentation is the least common. Stein et
al. described three different syndromes in
patients with pulmonary emboli. They
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Clifford C. Cloonan, MD
Breathing
tory and physical exam findings suggestive of deep vein thrombosis, it is important not to dismiss these findings or assume they are psychogenic in origin.
When combat conditions permit such patients should be evacuated to a level of
care capable of making this diagnosis; this
generally means a facility with a CT scanner.
4.5% of all cardiac arrests presenting to
emergency departments are secondary to
pulmonary embolus.190
Although one of the most common abnormalities on physical examination is
tachycardia, Green and coworkers191
found that almost 70% of patients with
pulmonary emboli younger than 40 and
approximately 30% of them older than 40
presented with heart rates less than 100
beats/min. Even tachypnea, which is more
consistently present than tachycardia, is
absent in 5% to 13% of patients with pulmonary emboli.188, 191 A low grade temperature is present in 14% of patients with
pulmonary embolus but this finding is
usually not helpful in making a diagnosis
of pulmonary embolus as it more commonly suggests pneumonia rather than
PE.192 Other physical examination findings common in pulmonary embolus include pleural friction rubs, rales, cyanosis,
and evidence of phlebitis; but in as many
as 58% of patients with proven PE the
physical examination fails to reveal any
clues as to the proper diagnosis.191 To
summarize, while the clinical findings of
tachycardia, tachypnea, dyspnea, hemoptysis, syncope, pleuritic pain and a pleuritic friction rub may be present in patients
with pulmonary emboli these findings are
neither sensitive, nor specific for this condition and, as noted above, these findings
are likely to be less commonly present in
young combatants than in the general
population.
More important than recognizing and
quickly evacuating all patients with a reasonably high probability of deep vein
thrombosis and pulmonary embolus is to
know how to prevent these conditions.
Encouraging combatants to stretch and
move their legs frequently during long
trips will help prevent the formation of
DVTs and keeping well hydrated has also
been
recommended.193
Compression
stockings have been proven to be of benefit in prevention of symptomless DVTs in
air travelers194 but this is not a practical
solution for most combatants; however in
those who are at high risk this might not
be an unreasonable suggestion.
While not shown to be highly efficacious
in preventing pulmonary emboli aspirin
has been shown to have some benefit,195
preventing four fatal pulmonary emboli
per 1000 in a multi-center trial. Although
not an issue in this discussion aspirin has
also demonstrated efficacy in the prevention of myocardial infarction.196 The problem with aspirin, of course, is that recommending that combatants take a drug that
helps prevent clotting is not entirely satisfactory and the risk-benefit ratio for most
combatants would weigh against such a
recommendation. This may not be true for
all, however, as some senior officers may
well be at greater risk of death from pulmonary embolus or myocardial infarction
than from enemy fire under certain circumstances, particularly if they have had
either of these conditions in the past.
What all this means to the medical care
provider in the forward areas of the battlefield is that it is important to be aware that
combatants, particularly those with risk
factors as described above, are at risk for
pulmonary emboli. When physical exam
findings are present in such patients that
suggest pulmonary embolus, such as unexplained dyspnea, tachypnea, tachycardia, and syncope; and when there are his-
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Clifford C. Cloonan, MD
Breathing
serious manifestation with symptoms
ranging from mild, with only dyspnea
and/or tachypnea, to severe and indistinguishable from the adult respiratory distress syndrome. About half of patients
with fat embolism syndrome develop severe hypoxemia and require ventilatory
support.199-201
To be complete it is also important to note
that emboli may not only arise from a venous thrombosis but may be caused by fat
originating from the marrow of a long
bone or the pelvis following a fracture.
Although fractures are common in combatants there is no evidence that fat emboli
are common clinical problem in combat
casualties; but subclinical fat emboli almost certain do occur.197, 198 Symptoms of
fat emboli generally do not immediately
follow injury but occur one to two days
later so this is not a problem likely to be
seen in the prehospital environment. This
syndrome should, however, be suspected
if typical symptoms occur in a casualty
with a long bone or pelvic fracture. The
classic triad of fat embolus symptoms is
hypoxemia, neurologic abnormalities, and
a petechial rash; but classic presentations
are uncommon. The respiratory distress
syndrome is the earliest, most common
As there is nothing that can be done for a
casualty with fat embolus in the field it is
only important for prehospital providers to
recognize when this clinical syndrome
may be present and to quickly evacuate
any such patients to an appropriate level
of care. The only measure of prevention
relevant in the prehospital environment is
to minimize movement of all fracture
fragments to the fullest extent possible as
manipulation of fractures has been shown
to be a cause of fat emboli.
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Clifford C. Cloonan, MD
Breathing
Summary
Specifically they must pay particular attention to the environmental factors (altitude, presence of atmospheric contaminants), mechanism of injury, and the casualty’s respiratory rate and depth and, when
available, to the oxygen saturation.
Injuries to the chest are among the most
fatal to combat casualties and respiratory
problems in general, because of their potential lethality, present a challenge to prehospital providers who must be able to
sort those casualties with minor problems
from those with potentially life threatening problems. In order to be able to properly diagnose respiratory problems the
pre-hospital provider must understand basic respiratory physiology and pathophysiology, the difference between ventilation and oxygenation, and the common
causes of dyspnea in combat casualties.
They must also have a basic understanding
of the epidemiology of thoracic injuries
and respiratory difficulties in combatants
so that they can make informed therapeutic and evacuation decisions. The diagnostic tools available to pre-hospital personnel to diagnose thoracic and respiratory
problems are limited so it is very important that pre-hospital military health care
providers be skilled at acquiring and properly interpreting the casualty’s history,
general appearance, and physical exam.
Commanders, trainers, and suppliers of
military prehospital personnel must utilize
epidemiologic information and an understanding of the potential risks of various
interventions such as needle thoracentesis
for tension pneumothorax, use and application of pre-hospital oxygen, and intubation/ventilation, to make decisions about
what pre-hospital procedures providers
should be trained, equipped, and authorized to perform. Because of the difficulty
in accurately diagnosing potentially life
threatening chest and lung problems in the
combat environment it is vitally important
that prehospital personnel be provided
simple-to-use, durable, and effective diagnostic tools for assessing ventilation problems and intra-thoracic pathology.
50
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Breathing
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Hirsh J, Hull RD, Raskob GE. Clinical features and diagnosis of venous thrombosis. J Am Coll Cardiol. Dec 1986;8(6 Suppl B):114B-127B.
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Wells PS, Hirsh J, Anderson DR, et al. A simple clinical model for the diagnosis of deep-vein thrombosis combined with impedance plethysmography: potential for an improvement in the diagnostic
process. J Intern Med. Jan 1998;243(1):15-23.
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Barritt DW, Jordan SC. Anticoagulant drugs in the treatment of pulmonary embolism. A controlled
trial. Lancet. Jun 18 1960;1:1309-1312.
183.
Hull R, Delmore T, Genton E, et al. Warfarin sodium versus low-dose heparin in the long-term treatment of venous thrombosis. N Engl J Med. Oct 18 1979;301(16):855-858.
184.
Douketis JD, Kearon C, Bates S, Duku EK, Ginsberg JS. Risk of fatal pulmonary embolism in patients
with treated venous thromboembolism. Jama. Feb 11 1998;279(6):458-462.
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Heit JA, Silverstein MD, Mohr DN, Petterson TM, O'Fallon WM, Melton LJ, 3rd. Predictors of survival
after deep vein thrombosis and pulmonary embolism: a population-based, cohort study. Arch Intern
Med. Mar 8 1999;159(5):445-453.
186.
Stein PD, Henry JW. Clinical characteristics of patients with acute pulmonary embolism stratified according to their presenting syndromes. Chest. Oct 1997;112(4):974-979.
187.
Riedel M. Acute pulmonary embolism 1: pathophysiology, clinical presentation, and diagnosis. Heart.
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188.
The urokinase pulmonary embolism trial. A national cooperative study. Circulation. Apr 1973;47(2
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189.
Brilakis ES, Tajik AJ. 82-year-old man with recurrent syncope. Mayo Clin Proc. Jun 1999;74(6):609612.
190.
Kurkciyan I, Meron G, Sterz F, et al. Pulmonary embolism as a cause of cardiac arrest: presentation
and outcome. Arch Intern Med. May 22 2000;160(10):1529-1535.
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Green RM, Meyer TJ, Dunn M, Glassroth J. Pulmonary embolism in younger adults. Chest. Jun
1992;101(6):1507-1511.
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Stein PD, Afzal A, Henry JW, Villareal CG. Fever in acute pulmonary embolism. Chest. Jan
2000;117(1):39-42.
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Schobersberger W, Schobersberger B, Mittermayr M, Fries D. Travel-induced thrombosis: an update.
Wien Med Wochenschr. 2002;152(17-18):445-449.
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Scurr JH, Machin SJ, Bailey-King S, Mackie IJ, McDonald S, Smith PD. Frequency and prevention of
symptomless deep-vein thrombosis in long-haul flights: a randomised trial. Lancet. May 12
2001;357(9267):1485-1489.
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196.
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Trialists' Collaboration. Bmj. Jan 8 1994;308(6921):81-106.
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198.
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199.
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59
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Breathing
200.
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Copyright 2007
The Brookside Associates, Ltd.
All Rights Reserved
60
Immediate Care of the Wounded
Clifford C. Cloonan, MD, FACEP
COL (ret) U.S. Army
Associate Professor
Department of Military & Emergency Medicine
Uniformed Services University of the Health Sciences
“It will be tragic if medical historians can look back on the World War II period and
write of it as a time when so much was learned and so little remembered.”1
Beecher H. Early Care of the Seriously Wounded Man. JAMA. 1951;145(4):193-200]
Henry K. Beecher - Father of the prospective, double-blind, placebo-controlled clinical
trial.
“It is highly desirable that anyone engaged in war surgery should keep his ideas fluid
and so be ready to abandon methods which prove unsatisfactory in favour of others
which, at first, may appear revolutionary and even not free from inherent danger.”2
Bailey H, ed. Surgery of Modern Warfare. 2nd ed. Edinburg: E & S Livingston; 1942;
No. 1. – Hamilton Bailey, Reknown British Surgeon
1
Circulation
“…the only good thing that can be said of shock is that by enfeebling the circulation it
may prevent so great a loss of blood as might otherwise occur.”3(p.9)
J.J. Chisolm, Confederate Surgeon – Manual of Military Surgery
All bleeding stops…eventually4. [Attributed to Guy de Chauliac (1300-1370)]
2
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
Hemorrhagic Shock
Introduction
The primary circulatory problem on the
battlefield is shock; specifically hemorrhagic shock. Causes of hypovolemic
shock such as massive burns and dehydration from a variety of causes, and
neurogenic, cardiogenic, septic, and
anaphylactic shock all occur in combat
casualties but much more rarely. Hemorrhagic shock, therefore, is the primary
focus of the following discussion. The
other forms of shock will be briefly discussed at the end of this section.
Exsanguination is the single most common cause of death on the battlefield;
therefore the prevention of exsanguination at or near the point of wounding
must be the single most important medical task. No hospital, no matter how advanced, and no surgeon, no matter how
skilled, can save a wounded patient who
has exsanguinated. Thus it is true, as Dr.
Nicholas Senn, founder of the Association of Military Surgeons of the United
States, once said, “The fate of the
wounded lies in the hands of the ones
who apply the first dressing.” Most of
those who die on the battlefield do so
within minutes of wounding. Few of
these patients with rapidly exsanguinating wounds can be saved regardless of
the level of care provided; most would
die even if they were wounded right outside a Level I trauma center. As noted
by Col. Gray during World War I, “The
haemorrhage that takes place when a
main artery is divided is usually so
rapid and so copious that the wounded
man dies before help can reach
him.”3(p.44)
Pathophysiology and
Manifestations of Hemorrhagic
Shock
A first century Roman savant, Aulus
Cornelius Celsus, has been credited with
describing hemorrhagic shock in vivid
terms that remain accurate today.8 He
reputedly said, “When much blood is
lost, the pulse becomes feeble, the skin
extremely pale, the body covered with a
malodorous sweat, the extremities
frigid, and death occurs speedily.” In the
late 1800s, Samuel Gross described
shock as being “a rude unhinging of the
machinery of life”9, 10 and John Warren
called shock “A momentary pause in the
act of death.”11 Despite great advances
in hospital-level care, assessment and
management of shock in the field remain little changed since at least World
War II.
Furthermore, a sizeable number who
could have been saved had care been
immediately available die because the
circumstances of combat preclude the
rapid delivery of such care. An analysis
of 98 Vietnam casualties who died from
exsanguination revealed that nearly 20%
had sustained injuries that, in ideal circumstances, could have been controlled
with a tourniquet and/or appropriately
applied direct pressure.5-7 But some
casualties with potentially lethal hemorrhage can be saved and it is upon this
group the combat medical provider must
focus.
Types of Shock
Many different types of shock have been
described. Shock is generally classified
by cause or by underlying pathophysiology. Two or more types are often combined in a single patient, for example,
hypovolemia may occur with septic
shock and cardiogenic shock may occur
when other types of shock exist. Regard-
3
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
less of the classification, the underlying
defect is always inadequate tissue perfusion. Other causes of hypovolemic
shock include dehydration, burns, and
“third spacing” of fluid into the peritoneum or other extravascular spaces. Although the focus of the discussion
herein is hypovolemic shock, other
types of shock such as cardiogenic
shock, neurogenic or vasogenic shock,
anaphylactic and septic shock do occur
in combat casualties,.
Increases in heart rate (variable) and in
cardiac contractility also maintain cardiac output. The quality of the pulse remains normal to somewhat weakened in
strength (pulse pressure is normal to
slightly decreased). Sympathetic constriction of the arteries leads to an increased peripheral vascular resistance
that also helps to maintain blood pressure. This arteriolar constriction decreases capillary flow producing the
cool skin so characteristic of patients in
shock. Catecholamine release also produces bronchodilation, with associated
improved air exchange.
Stages of Shock
Shock is typically described as occurring in stages, although there are rarely
distinct boundaries or well-defined
characteristics that differentiate one
stage from the next. Shock exists on a
continuum that is unique in any given
patient. The stages of shock, as described in most texts, are compensated,
decompensated,
and
“irreversible”
shock.
The primary physical findings in compensatory shock are slightly delayed
capillary refill and cool, slightly pale,
skin. Other manifestations of shock may
include mild to moderate thirst and depression, with no alteration in mental
status. If the underlying cause remains
untreated and continues unabated, the
compensatory mechanisms eventually
collapse. The progression of shock in
the microcirculation produces a sequence of changes in capillary perfusion. Oxygen and substrate delivery to
the cells supplied by these capillaries
decreases, resulting in anaerobic metabolism that produces a lactic acidosis.
When severe hypotension is present,
oxygen delivery is markedly reduced
and tissue oxygen extraction (percent of
available oxygen extracted) is increased
to meet demand. It should be noted that
acidosis facilitates oxygen extraction at
the cellular level by shifting the oxygenhemoglobin dissociation curve to the
right. For this reason shock-associated
acidosis should never be treated with
sodium but rather by restoring cellular
perfusion.
Compensated Shock
Compensated shock involves some degree of decreased tissue perfusion however the body's compensatory responses
are sufficient to overcome the decrease
in available intravascular volume. Cardiac output and a normal systolic blood
pressure are maintained by sympathetic
stimulation. In this stage the rate and
depth of respirations increase, leading to
decreased PCO2 (compensatory respiratory alkalosis). This decrease is in response to decreased tissue perfusion and
its resultant lactic acidosis. Sympathetic
constriction of the large veins increases
the amount of blood in the arterial system contributing to the maintenance of
blood pressure and cardiac output (CO);
essentially providing a venous capacitance autotransfusion.
Capillaries become “leaky” and proteincontaining fluid leaks into the interstitial
spaces (leaky capillary syndrome). Arte-
4
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
riovenous (AV) shunts open, particularly in the skin, kidneys and gastrointestinal tract, diminishing flow to the
arterioles and capillaries in these organs.
Sympathetic stimulation produces the
pale, sweaty skin and rapid, thready,
pulse (significantly narrowed pulse
pressure) that Celsus described in the
first century. It also elevates blood glucose levels and dilates coronary, cerebral, and skeletal muscle arterioles while
constricting others. Blood is thus
shunted to the heart, brain, and skeletal
muscle with decreased capillary flow to
the kidneys and abdominal viscera
(autoregulation).
capacity may become great enough to
reduce the volume of available blood for
the great veins, further decreasing venous return and cardiac output. The viscera (lung, liver, kidneys and gastrointestinal mucosa) become congested due
to stagnant blood flow. The respiratory
system continues to attempt to compensate for the acidosis by increasing ventilation resulting in a partially compensated metabolic acidosis (decreased partial pressure of carbon dioxide [PCO2]).
Clotting mechanisms are affected leading to a hypercoagulable state that may
result in disseminated intravascular coagulation. Uncorrected this stage of
shock progresses to “irreversible” shock.
Decompensated Shock
“Irreversible” Shock
Without prompt restoration of circulatory volume, compensated shock progresses to decompensated shock. Decompensated shock is manifested by a
marked increase in heart rate, significantly prolonged capillary refill, and
reduced blood flow to critical organs. At
this stage, patients complain of marked
thirst and although their mental state
may remain clear, they are likely to be
apathetic unless stimulated. Urine output
decreases and eventually decreased
blood flow to the brain alters mental
status. As the shock state continues, the
precapillary sphincters relax, expanding
the vascular space. Postcapillary sphincters resist local effects and remain
closed, causing blood to pool or stagnate
in the capillary system producing capillary engorgement. Because increasing
hypoxemia and acidosis lead to opening
of additional venules and capillaries, the
vascular space expands greatly.
At this point, the body is no longer able
to maintain systolic pressure and both
systolic and diastolic pressures begin to
drop. The blood pressure may become
unrecordable, the pulse will become
very weak or even imperceptible, and
the pulse pressure will be narrowed to
such an extent that it may not be detectable with a blood pressure cuff.
“Irreversible” shock is manifested by
extreme tachycardia or, in some cases,
bradycardia, serious dysrhythmias, frank
hypotension, and evidence of multiple
organ failure. The skin is pale, cold, and
clammy and capillary refill is markedly
delayed. Patients in severe shock may
complain bitterly of thirst, if they are
able to speak. As cerebral blood flow
decreases, there may be alteration in
mental status manifested by apathy and
such patients may appear to suffer very
little. At this stage, patients may even
become comatose although in previously healthy, physically fit, young adult
soldiers, this tends to occur very late, if
at all, and is often followed rapidly by
death. In combat casualties, as a general
With decompensated shock complete
restoration of normal blood volume may
be inadequate to fill the vascular “container” (this has implications for fluid
resuscitation). The capillary and venule
5
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
rule, it is dangerous to assume that
shock is the cause of altered mental
status before ruling out other causes
such a head injury.
it is simply not possible to know at what
point shock has become “irreversible.”
Indeed, a World War II army medical
team sent to Anzio to study shock in
nearly 3,000 casualties made the following observation:
In “irreversible” shock, the partial pressure of oxygen (PO2) may drop but the
PCO2 usually remains normal or low
unless there is associated head or chest
injury that leads to hypoventilation.
Pulmonary capillaries become permeable, leading to pulmonary edema and
acute respiratory failure or adult respiratory distress syndrome (ARDS). Cardiac
ischemia may be present as a result of
decreased hemoglobin, lower oxygen
saturation, and decreased coronary perfusion secondary to diastolic hypotension. This ischemia may result in myocardial infarction and life-threatening
dysrhythmias.
The degree of wound shock, as we
saw it...precisely paralleled the
blood loss. Conversely, clinical recovery from shock resulted promptly
from the administration of whole
blood. Although we made intensive
search at the bedside of thousands
of wounded men...we never found a
clear case of irreversible shock, so
easily spoken of in published articles on this subject...The shock we
saw was caused by blood loss…it
was cured by blood administration.12(p. 672-681)
“Irreversible” shock is manifested by the
progression of cellular ischemia and
necrosis and by subsequent organ death
despite restoration of oxygenation and
perfusion. If capillary occlusion persists
for more than 1-2 hours, the cells nourished by that capillary bed undergo irreversible changes. The unperfused cells
can no longer use oxygen and metabolism stops. Hepatic failure usually occurs first, followed by renal failure, and
then heart failure. Gastrointestinal
bleeding and sepsis may result from
mucosal necrosis. Pancreatic necrosis
may lead to further clotting disorders
and severe pancreatitis. Pulmonary
thrombosis may produce hemorrhage
and fluid loss into the alveoli, leading to
death from respiratory failure.
Individual Manifestations of Shock
Although the various stages of shock are
described in terms of specific physiologic states the manifestations of shock
in a particular patient are determined, in
large part, by that patient’s pre-existing
physiologic status. Factors that influence
the response to a specific shockproducing insult include (1) age and
relative health (2) pre-existing physical
condition, and (3) pre-existing diseases
and use of medications that may impair
the body’s ability to mount an appropriate physiologic response. Elderly patients are less able to compensate and
thus tend to develop hypotension early.
Children and physically fit young adult
soldiers are able to compensate longer
but they tend to decompensate precipitously.
Despite these well-described pathophysiologic changes, the irreversibility
of “irreversible” shock has been questioned. The term, “irreversible shock”
certainly has relevance in terms of
pathophysiology but in any given patient
Those who provide care at or near the
point of wounding need to be aware that
mortally wounded soldiers may not
comprehend the severity of their injuries
6
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
and may only display outward signs of
shock just before death. Even vital signs
may misleadingly remain within the
normal range for a surprisingly long
time. The military historian S.L.A. Marshall describes one such circumstance as
follows, “Millsaps [started across the
river with one volunteer]...The man
soon began to fall behind. Millsaps
asked: “Something wrong with you? He
answered: “I don’t think so.” Then
Millsaps stripped the man’s jump jacket
away and found six bullet holes in his
upper right arm and shoulder; the soldier
had not been aware of his wounds until
that moment. The soldier collapsed [and
died].
Millsaps
continued
on
alone.”13(p.183)
tial thirst is almost always present in
severe shock.
When obtained at a single point in time,
there is no single sign or symptom that
can be used to reliably separate those in
shock from those not; or to grade the
severity of shock in an individual patient. There is simply no pathognomic
sign or symptom of shock. Most important in making the diagnosis of shock is
observation and repeated assessment
over time. Particular attention should be
given to observing the trend of the pulse
and the pulse pressure (systolic minus
diastolic blood pressure). A rising pulse
rate, a falling blood pressure, and a narrowing pulse pressure should always
alert the medical provider to the likelihood of shock, especially if associated
with a cool skin, in a patient who has
been in a warm environment.
Identifying the Patient in
Hemorrhagic Shock at or Near the
Point of Wounding
Specific Tests for Shock
Shock should be assumed in the patient
who has a weak, rapid, pulse (narrow
pulse pressure), and a wound consistent
with a shock state. It should be noted
that severe extremity wounds are often
associated with shock. The Board for the
Study of the Severely Wounded in
World War II found that, “…[T]he
greatest loss of hemoglobin occurs in
wounds that involve compound fractures
of long bones or traumatic amputations.”12(p.676) Certainly it was patients
with these types of wounds who survived long enough to reach the shock
tents on the beach at Anzio. In fact, this
study showed that the blood loss associated with compound long bone fractures
was greater than that seen in traumatic
amputation.
Blood Pressure
The general inability to use, with any
beneficial effect, a single measurement
of blood pressure to diagnose shock has
long been recognized. Sir Zachary Cope,
a pre-eminent surgeon of his day with
considerable military experience in
World War I, made the following observations about the utility of the blood
pressure in diagnosing shock:
Though in general, blood loss increased with tissue damage, large
blood loss might occur with small
wounds... [There is] difficulty in
recognizing those who had lost
moderate amounts of blood, for patients who only had 70 or 80 percent
of normal blood-volume might still
maintain a normal blood pressure,
though usually (but not always) they
at the same time had a fast pulse
It is again worth pointing out that except
for patients with head wounds, the badly
injured are nearly always lucid. Importantly the degree of thirst that is present
in shock is often unappreciated; substan-
7
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
and a pale face. A few of the patients [in shock] even presented a
raised systolic blood pressure, while
of those with a blood pressure of
under 100 mm. Hg., some had rapid
pulses, others only slightly more
rapid than normal. A few, and these
generally patients over fifty years,
showed a pulse rate under seventy.
In younger people the blood pressure was better maintained but the
pulse rate tended to be faster...As a
rule the blood pressure was proportional to the degree of injury and the
reduction of blood volume, but occasionally extreme vasoconstriction
maintained the blood pressure at a
deceptive level, for example, 95 mm
Hg, although in such cases the pallor was intense.”14
shown that blood pressure and heart rate
are unreliable indicators of shock in
young trauma patients.”17 A recent study
by Shoemaker et al. comparing invasive
with non-invasive monitoring of intensive care unit (ICU) patients found that
the average mean arterial pressure
(MAP) initially recorded in survivors
was only slightly higher than that of
nonsurvivors.18
One final concern with relying on blood
pressure to assess for shock is the accuracy of the blood pressure measurement
itself. Potential problems include (1) the
reliability of the provider who obtains
the blood pressure, (2) the reliability of
the equipment used to obtain the blood
pressure, 19, 20 and (3) the ability of the
equipment to perform outside of the
normal physiologic range. Moskowitz
and Reich note that, “The skill of the
practitioner in detecting Korotkoff
sounds and the speed of cuff deflation
are potential sources of error in blood
pressure measurement.”21 Hypotension
produces hypoperfusion of the extremity
with a resultant underestimation of
blood pressure when assessed using the
standard method.22 Creamer et al.23
demonstrated that the cuff pressures of
patients in cardiogenic shock were
poorly correlated with those obtained by
direct monitoring of MAP.
More recently Capan and Miller, in their
article on resuscitation, make the comment that, “equating a normal systemic
blood pressure (or pulse) with normovolemia during initial resuscitation may
lead to loss of valuable time for treating
the underlying hypovolemia.”15 During
World War II, Henry K. Beecher said,
Possibly, too much attention has
been given to the fact that on many
occasions [patients in shock may
have a normal blood pressure]...[T]his has led to a tendency
to dismiss the blood pressure as a
helpful sign even when it is low - a
fatal error, on some occasions.
More helpful than the level of the
blood pressure, is the direction of its
swing - a falling blood pressure, a
rising pulse rate, are in most cases
an urgent indication of the need for
blood.”16
Pulse Rate and Pulse Pressure
Regarding the efficacy of pulse rate and
pulse pressure in the assessment of
shock during World War II, The Board
for the Study of the Severely Wounded
noted that pulse rate is influenced by too
many factors to be of great value by itself in the estimation of shock severity.24
The Board did indicate, however, that
the quality of the pulse and its upward
or downward trend are most important.
In a study on shock conducted by the
Dr. Colin Mackenzie, in his article “Anesthesia in the Shocked Patient” observes that, “It has been repeatedly
8
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
Board24, the average, minimum and
maximum pulse rates were the same in
all degrees of shock. This surprising
finding was explained as follows:
Despite a long-standing recommendation to use the ability to obtain a
pulse at the radial, femoral, and carotid arteries to estimate blood pressure (palpable radial pulse ≥ 80 mm
Hg systolic blood pressure, palpable
femoral pulse ≥ 70 mm Hg, and palpable carotid pulse ≥ 60 mm Hg systolic), there appears to be no scientific basis for this common belief. A
2000 study by Deakin and Low33
published in the British Medical
Journal compared the presence or
absence of radial, femoral, and carotid pulses with intra-arterial blood
pressure measured in the operating
room. They found that, “The mean
blood pressure and reference range
obtained for each group indicate that
the guidelines overestimate the systolic blood pressure associated with
the number of pulses present.” This
author was unable to find any other
studies that address the efficacy of
this commonly used procedure to
estimate blood pressure but empirically there appears to be a general
correlation.
1. The tachycardia in the lesser
degrees of shock may have been
due in part to excitement, and
2. In some cases, the elevated
pulse rate (and accompanying
vasoconstriction) may have
been adequate to ward off the
signs of shock.
3. Further, even patients judged to
be in severe shock could have a
pulse rate as low as 60 beats per
minute.
Of greater significance than the pulse
rate was its volume, which often is decreased so far in severe shock that the
pulse can no longer be felt [narrow pulse
pressure]. Beecher et al. noted that as
the severity of shock increases there is a
significant and progressive decline in
the pulse pressures as the severity of
shock increases.24
The importance of measuring and tracking the pulse pressure of patients in
shock was also emphasized by Sir Zachary Cope, who said, “...a rapid pulse of
low volume was a more constant indication of danger than a fall of blood pressure; a fall of blood pressure was sometimes a comparatively late event in circulatory failure after wounding.”14 Occasionally patients in shock present with
a normal or paradoxically decreased
pulse rate. This condition has often been
associated with ruptured ectopic pregnancy.25, 26 and penetrating abdominal
trauma.27-29 but it has also been seen in
hemorrhagic shock due to other
causes30-32.
General Appearance and Mental
State
Previously healthy, physically fit soldiers are so capable of compensating
and autoregulating blood flow to the
brain that even when blood loss has
been massive, the usual mental lethargy
that has often been described in shock
may be absent and instead the patient
may demonstrate unexpectedly normal
mental acuity. This might easily deceive
an inexperienced observer into thinking
that shock is not present. Cope found
that “In shock the mental state was usu-
9
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
ally rational…”14 The Board for the
Study of the Severely Wounded during
World War II stated that assessing mental status was not useful by itself but
was helpful when combined with other
findings, and noted that there was some
correlation between mental status and
degree of shock.24
were consistent with hypovolemia, and
they concluded that although the “tilt”
test might differentiate patients with
massive volume deficits from those
without, attempting to do this test in
critically injured patients was both unnecessary and unsafe.35
In a study assessing the usefulness of the
tilt test in identifying significant intravascular volume depletion, Levitt et
al. concluded that defining a “positive”
tilt test appears to be impossible, and
that although it is considered to be “the
standard of care in evaluation of the hypovolemic patient,” orthostatic vital
signs have not been scientifically validated.36 In a 2000 review, Dabrowski et
al. questioned the accuracy of this test in
diagnosing early shock when they noted
that approximately 50% of normovolemic patients in the Koziol-McLain
et al. study35 exhibited positive orthostatic changes.37
Orthostatic Vital Signs
Orthostatic vital signs are used specifically to assess for hypovolemia. Orthostatic vital signs consist of blood
pressure and pulse measurements obtained first when the patient is lying
down and then from a standing or sitting
position. Although typically used to assess intravascular volume status the validity of this test is in dispute. Commonly used parameters are the following
differences between lying and standing
measures:
>15-20 beat-per-minute increase in
pulse rate
- The greater the difference, the higher
the specificity and the lower the sensitivity for finding clinically significant
hypovolemia
Witting et al. found that in order to reliably separate patients with no blood
loss from those with a 450-mL blood
loss, the criteria for pulse had be set at a
20-point difference from lying to standing.37 Even this sizeable difference produced a large number of false positives
(normal patients identified as being abnormal). The authors also concluded that
measurement of blood pressure as part
of this test was without value and might
actually provide misleading information.
Although orthostatic vital signs are
widely used to detect intravascular hypovolemia, a study by Baraff et al.34
found that, “No combination of orthostatic vital sign changes with a specificity of 95% or higher was sensitive
enough to reliably detect an acute 450
ml blood loss.” Koziol-McLain et al.
found that many normal (euvolemic)
patients had orthostatic vital signs that
None of this should be interpreted to
mean that orthostatic vital signs are unable to identify many, if not most, patients in moderate to severe shock. It is,
however, probably inappropriate to subject most patients in severe shock to this
test because standing causes decreased
perfusion of the brain and, at this stage,
other findings will surely be present. If
orthostatic vital signs are measured and
>10-20 mm Hg decrease in systolic
blood pressure
>10-15 mm Hg decrease in diastolic blood pressure
10
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
are grossly positive, particularly when
other findings also suggest shock, the
results should, most certainly, not be
ignored.
rather to emphasize that many factors
can render this test incapable of identifying early shock and to point out that
capillary refill testing will over-diagnose
shock, particularly in women and the
elderly, and in cold, poorly lit, environments. As with orthostatic hypotension,
if a patient with other signs and symptoms of shock and a mechanism of
wounding consistent with shock has a
positive test, e.g. delayed capillary refill,
the patient is, almost certainly, in shock.
Capillary Refill Test
Despite being one of the characteristic
assessments in making a diagnosis of
shock, delayed capillary refill has been
shown to be an unreliable indicator of
decreased intravascular volume. Unfortunately the efficacy of this test has not
been well studied, particularly in settings where it is most relied upon, the
prehospital and emergency department
environments. In these settings, there is
wide variability in a number of important factors including lighting, temperature, and skill level and experience of
the provider making the assessment.
Hemoglobin Concentration Test
Although not a test that would generally
be done at, or immediately near, the
point of wounding, a test for hemoglobin concentration can certainly be conducted at a Battalion Aid Station. The
effectiveness of this test in diagnosing
shock has not been established. During
World War II, Beecher found “no early
correlation between hemoglobin or hematocrit levels and circulating blood
volume.”1(p.194)
Furthermore, significant gender and age
differences in response to this test have
been shown, even in otherwise normal
patients. Schriger and Baraff, in one of
the few studies of this commonly used
test, found that, “The upper limit of
normal for adult women should be
changed to 2.9 seconds and the upper
limit of normal for the elderly should be
changed to 4.5 seconds.”39 The authors
also questioned whether the temperature
dependence of the test may compromise
its reliability in the prehospital setting.
This study lead Knopp to make the following editorial comment, “Given current ‘normal values’ and the variables
of environmental temperature, age, sex
and questions regarding the interpretation [which is affected by such things as
lighting], one is left with the impression
that at present capillary refill testing
may be unreliable.”40
There is some evidence, however, to
suggest that an early low hemoglobin
and hematocrit concentration might be
of value as an indicator of acute, severe,
blood loss. In a study of the effect of
fluid resuscitation on hematocrit, Glick
et al. found, despite the current teaching
that hematocrit does not decrease immediately after acute hemorrhage, a 17%
decrease in hematocrit at 15 minutes
after the bleeding of splenectomized
dogs that stabilized with no further drop
during the remainder of the study.41
Knottenbelt, in a study of 1000 trauma
patients, also demonstrated that, although it is traditionally taught that the
body takes hours to respond to blood
loss by moving fluid into the capillary
circulation from interstitial spaces, patients who present with low initial he-
The preceding is not intended to imply
that assessing for capillary refill has no
place in the diagnosis of shock. It is
11
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
moglobin may have suffered significant
hemorrhage.42 In this study, a correlation between low initial hemoglobin
levels and mortality in trauma patients
was found. When there is significant
hemorrhage and hypotension, extracellular fluid is readily drawn into capillaries, producing the low hemoglobin that
is often seen on initial presentation in
victims of severe trauma. This anemia is
not caused by the dilutional effect of the
initial fluid resuscitation bolus. Unfortunately there are also patients in hemorrhagic shock who present with hemoglobin and hematocrit concentrations
within the normal range, so this test
cannot be solely used to diagnose shock.
Fluid Resuscitation
Non-Blood Fluids
In order to have the best understanding
of where we are today in terms of nonblood fluid resuscitation of patients in
hemorrhagic shock, it is important to
know the history of this practice. In
1832, while England was in the midst of
a cholera epidemic, a 22-year-old doctor
named William B. O’Shaughnessy recognized the underlying pathophysiology
of cholera that was leading to death and
he proposed a solution.44, 45 He noted
that, “…the [two] indications of
cure…are…to restore the blood to its
natural specific gravity [and] to restore
its deficient saline matters…The first of
these can only be effected by absorption,
by imbibition [drinking], or by the injection of aqueous fluid into the veins.”
“When absorption is entirely suspended…in those desperate cases,”
O’Shaughnessy recommended, “the injection into the veins of water holding a
solution of the normal salts of the
blood.” Dr. Thomas Latta was the first
to apply O’Shaughnessy’s advice.45
Reading the reports of doctors who had
implemented his suggestions, Dr.
O’Shaughnessy stated in the Lancet on 2
June 1832 “…the results of the practice
[intravenous infusion of a saline solution]…exceed my most sanguine anticipations.”47
Once again, however, a patient who presents immediately after injury with a
low hemoglobin/hematocrit and other
signs or symptoms of shock should be
presumed to be in shock. It is ill-advised
to ignore positive tests, even ones that
are not particularly sensitive or specific,
especially when they are being applied
to a population with a relatively high
probability of having the condition for
which the test is being conducted.
Future Tests for Shock
Based upon the finding that in experimental porcine hemorrhagic shock,
changes in intestinal perfusion are the
most rapid, sensitive indicators of acute
blood volume loss,43 wounded soldiers
in the not-too-distant future might be
given a “pill” to swallow that will monitor gut pH and will transmit this information to an external sensor that could
track changes in intestinal perfusion as
an early marker for shock. Someday,
measurement of gut pH by prehospital
personnel will allow for early, accurate,
diagnosis and treatment of shock.
Since 1832, the benefits of non-oxygen
carrying electrolyte solutions have remained undisputed when the primary
need is “to restore the blood to its natural specific gravity [and] to restore its
deficient saline matters” and [underlining added for emphasis] when the oral
route, for whatever reason, is not a viable alternative.44 The use of saline and
related fluids for the treatment of hem12
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
orrhagic shock did not come into practice until following the 1883 recommendation of Charles E. Jennings’ (a British
clinician and physiologist). He stated
that in “…most of the instances where
[blood] transfusion is called for, I unhesitatingly advise the intravenous injection of [saline] fluid as being certain
in its action, comparatively free from
danger, and not requiring any special
skill in its performance.”48, 49(p.193)
combat casualties observed that administration of intravenous fluids to patients
with uncontrolled hemorrhage was potentially detrimental.54, 55(pp 25,189), 56 During World War I, Gordon Watson, Consulting Surgeon to the British Second
Army, observed that the effects of infused saline were “too often transitory –
a flash in the pan – followed by greater
collapse than before.”49(p.100) During the
Spanish Civil War, Dr. Douglas Jolly
noted that,
In the early 1880s another British physiologist, Sidney Ringer, developed his
“Ringer’s Solution” that evolved into
Ringers lactate, a resuscitation fluid that
remains the American College of Surgeons’ Advanced Trauma Life Support
(ATLS) recommended trauma resuscitation fluid.50(p.97)
“There is always a commendable
desire in the Classification Post
[read Battalion Aid Station] to do
something active in cases of severe
abdominal haemorrhage.
Sometimes this “first-aid” takes a dangerous form – i.e. the administration of
large quantities of intravenous saline
or glucose. The patient has already
lost so much of his circulating haemoglobin that he cannot afford to
have the remainder washed into the
peritoneal cavity…The presence of
gum Arabic [read Dextran] in the
saline makes no real difference.55(p.189)
The scientific basis for infusing nonoxygen carrying fluids into patients in
hemorrhagic shock has been established
in numerous animal studies. When animals are exsanguinated in a controlled
manner (Wigger’s or modified Wigger’s
method) in a laboratory setting, those
resuscitated with either or both crystalloid and colloidal intravenous fluids
have a better probability of survival than
those not similarly treated.51(p.138-139)
Recently these early empiric observations by military medical officers have
been confirmed with controlled scientific studies. In 1991, Bickell et al. demonstrated the detrimental effect of aggressive intravenous crystalloid resuscitation in pigs with uncontrolled hemorrhage.52, 57 In 1994 this was followed up
with a human trial demonstrating that
patients with penetrating wounds of the
torso (uncontrolled bleeding) who were
resuscitated with intravenous fluids
prior to arrival at a hospital fared worse
than those who were not given intravenous fluids.52
Only relatively recently have human
studies been done that could establish
with any certainty that trauma patients
treated with intravenous fluids have a
better chance of survival than those not
similarly treated.52, 53 Despite the widespread and long history of use of saline
and related fluids to resuscitate patients
with blood loss there has, for some time,
been evidence that in some trauma victims the use of these fluids is worse than
useless. Throughout the first half of the
20th Century, despite a lack of corroborative studies, military physicians with
substantial experience in caring for
These findings have generally been confirmed by other investigators, who also
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
found that animals with uncontrolled
hemorrhage fare worse if aggressively
resuscitated with fluids.58-60 Some of
these studies show that animals resuscitated with minimal to moderate fluids to
specific physiologic endpoints do better
than both those aggressively resuscitated
and those not given any fluids. A study
by Kim et al. showed improved survival
when animals with uncontrolled bleeding were resuscitated to a pressure of 40
mm Hg with Ringers lactate and a colloidal plasma substitute as compared to
resuscitation with just Ringers lactate;
both groups had better survival than
those given no fluid resuscitation.60 In
1999, Soucy et al. reported improved
survival in rats with tail resections when
resuscitation was accomplished with a
“moderate” volume (80 ml/Kg) given at
a fast rate (17.8 ml/Kg/min) as compared to non-resuscitated rats (60% survival as compared with 16.7% survival).61 Other studies have also shown
the benefit of moderate volume resuscitation over no resuscitation, particularly
when evacuation time to surgery is
long.62, 63
approach to the management of hemorrhagic shock in casualties with the prolonged transport times and long delays
until definitive surgery typical of combat situations. The appropriate mean
arterial pressure that would minimize
ongoing blood loss yet allow for adequate organ perfusion to prevent multiorgan dysfunction has yet to be determined.65
The American College of Surgeons’
ATLS guidelines50 continue to recommend that initial resuscitation of patients
with blood loss be done with intravenous crystalloid at a ratio of 3 mL for
every 1 mL of estimated blood loss.
This "three-for-one" rule is derived from
the observation that most patients in
hemorrhagic shock require as much as
300 mL of electrolyte solution for each
100 mL of blood loss. Applied blindly,
these guidelines can result in excessive
or, in some cases, inadequate fluid administration.66 The use of bolus therapy
with careful monitoring of the patient's
response can moderate these extremes.
Estimation of external blood loss, even
by medical personnel, is notoriously
inaccurate and internal blood loss cannot
be estimated except during surgery.
Unfortunately because of difficulties
with obtaining informed consent, the
results of Bickell’s human trial have not
been confirmed. It should be noted that
in Bickell’s human trial, the prehospital
transport times were very short (< 15
minutes) and the times from wounding
to surgery were generally under an hour.
Concerns have been expressed regarding
application of the “no prehospital fluids
to patients with uncontrolled truncal
hemorrhage” rule when the time from
wounding to surgery is hours, as is the
usual case in combat.64 The dilemma of
maintaining perfusion to the brain (and
other vital organs) in patients with prolonged hypovolemia, especially in those
with closed head injuries, remains. Further study is required to confirm the best
The ATLS correlation of various physiologic parameters to specific amounts of
blood loss is not well supported by good
studies and really can’t be used to make
the 3 mL crystalloid for every 1 mL
blood loss calculation.50 In a study using
splenectomized canines, Glick et al. examined the efficacy of various fluid resuscitation strategies and the effect of
fluid resuscitation and hemorrhage on
hematocrit concentration.41 In the group
treated with the recommended replacement of blood loss with crystalloids at a
3:1 ratio, there was a significant decrease in platelets and a significant increase in the prothrombin time com-
14
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
pared with those resuscitated at a 1:1
ratio. Although the 3:1 group did
achieve a transient supranormal hemodynamic state, this had no distinct benefit over time. The conclusion of this
study was that the recommended 3:1
resuscitation strategy had no advantage
over a 1:1 replacement strategy even in
a controlled hemorrhage model.
(2) Delayed operation: If a patient
must await surgical intervention
for a considerable period, even
though blood may be available,
there is no need to transfuse more
rapidly than necessary to achieve
these conditions, with one addition: when blood is available it is
desirable to administer it until the
skin loses the chill of shock and
becomes warm. As long as the
systolic blood pressure is not below a level of about 85 mm of
mercury, the mucous membranes
of good color, the skin warm and
the pulse of good quality, there is
no need to administer further
blood until surgical treatment is
available. To administer blood
beyond the quantity necessary to
achieve the condition mentioned,
before surgery is available, inevitably means that more blood must
be used than would otherwise be
the case. Blood or plasma will
leak into traumatized regions and
be needlessly wasted; the hazard
of an unnecessary number of
transfusions will be incurred …
Moreover, reasonable economy of
blood means that it will be more
abundantly available when need
for it is urgent (systolic blood
pressure below 80 mm mercury,
pulse of poor quality and patient
cold and pallid).
The following is the fluid resuscitation
approach to the combat casualty in
hemorrhagic shock that was recommended by Henry K. Beecher in World
War II. It is based upon his own observations and those of the other members
of the Board for the Study of the Severely Wounded of nearly 3,000 combat
casualties, 72 of which were in severe
hemorrhagic shock. It is surprisingly
similar to the current recommended approach:
Resuscitation should be graded. It is
important to rapidly restore a good
blood color and the systolic pressure to
an arbitrary level of about 85 mm of
mercury in subjects whose blood pressure had previously been normal. Once
these things have been accomplished,
the rate of infusion of blood or blood
substitutes depends on several factors:
(1) Delayed blood transfusion: If
blood for transfusion or operation
will not be available for a matter
of hours, infusion of plasma or
other blood substitute should be
rapid enough only to maintain the
aforementioned state (systolic
B.P. of 85). More rapid administration of plasma will elevate the
blood pressure to the level where
bleeding will be renewed or increased, with further and perhaps
disastrous loss of irreplaceable
(for the time being) hemoglobin.
(3) Surgery available: When surgery
is available, further transfusion of
blood is advisable so that the rising blood pressure is achieved at
the time the anesthesia is started.1
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
Holcomb, the current director of the
United States Army Institute for Surgical Research. This input was provided in
the form of a white paper entitled, Hypotensive resuscitation - algorithm for
AMEDD combat fluid resuscitation,
which was followed by a recent publication on the same topic in the Journal of
Trauma.67
They felt that,
Complete restoration to normal
blood volume or blood pressure is
not a necessary preliminary to successful surgery in previously healthy
young men…Operation [should be]
undertaken as soon as experience
has shown that the patient will tolerate it, indicated chiefly by a rising
blood pressure (85 mm mercury or
above), a falling pulse rate, a warm
skin and good color of the mucus
membranes. Delay in surgical intervention beyond the accomplishment
of these things requires the constant
support of the patient by blood or
blood substitutes and, in the end, the
use of needlessly large total quantities of these agents. Delay means
that infection will have progressed.
This is closely allied to a rising
death rate. Some patients, more often those with penetrating wounds
of the abdomen, will fail to show
any response to whole blood. Generally these patients are found to
have continuing concealed bleeding
or wide contamination of the peritoneal cavity. The failure of response
to the usual resuscitative measures
calls for a critical decision: the necessity of undertaking operation in
the patient in poor condition. This
bold decision may be life saving.”1
The bases for the following recommendations are:
(1) The consensus of the 2001
Combat Fluid Resuscitation
Conference, which was held at
the Uniformed Services University of the Health Sciences
(USUHS), Bethesda, Maryland,
in June 200168 and
(2) Recent studies that demonstrate
the value of moderate volume
resuscitation, particularly when
transport times may be long.58,
63, 69-73
There was unanimous agreement among
the attendees at the 2001 Combat Fluid
Resuscitation Conference that hypotensive resuscitation strategies were tactically relevant, physiologically sound
and should be utilized. There was also
general, although not universal, agreement on the type of fluid to utilize while
performing hypotensive resuscitation,
and there continues to be general
agreement that a low volume fluid administration is optimal (how low remains disputed). The fluid resuscitation
algorithm used in the 91W Health Care
Specialist Program at Fort Sam Houston
that follows is based on the following
assumptions:
Current Point-of-Wounding Fluid
Resuscitation Guidelines
Based upon recent information (above)
regarding fluid resuscitation, changes
have recently been made in the curriculum for combat medics. Those changes
are specifically based on input provided
to the AMEDD Center & School 91W
Health Care Specialist Program at Fort
Sam Houston, Texas, by COL John
• The tactical situation may or may
not allow for medical care
16
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
• Hemorrhage control is of paramount
importance
fluid resuscitation is required
• Stethoscopes and blood pressure
cuffs are rarely available or useful to
the frontline medic
2) Any significant extremity or truncal
wound (neck, chest abdomen or pelvis), with or without obvious blood
loss or hypotension, and irrespective
of blood pressure:
• A palpable radial pulse and normal
mentation are adequate and tactically relevant resuscitation endpoints to either start or stop fluid resuscitation. Both can be easily and
adequately assessed in noisy and
chaotic situations.
a. If the soldier is coherent and has
a palpable radial pulse, blood
loss has likely stopped. Start a
saline lock; do not give any fluids but re-evaluate as frequently
as the tactical situation permits.
b. Significant blood loss from any
wound and the soldier has no
palpable radial pulse, or is not
coherent (note: mental status
changes due to blood loss only,
not head injury):
• Intravenous (IV) access is important
for delivery of fluids and medication
and should be obtained early on any
casualty with a significant injury.
Only those casualties meeting criteria for resuscitation are given fluids
through a single 18-gauge saline
lock. When IV access is not possible, intraosseous infusion is a reasonable alternative
i. STOP THE BLEEDING using direct pressure: hands
and gauze rolls, hemostatic
dressings, hemostatic powder, [QuikClot – see following discussion on hemostatic agents], with or without adjuncts like Ace bandages—is primary when
possible. Extremity injuries
may require the temporary
use of an effective arterial
tourniquet. However, >90%
of hypotensive patients suffer from truncal injuries,
which are unavailable to
these resuscitative measures.
• The capacity for prehospital fluid
resuscitation depends on the
amount, both weight and volume, of
fluid that can be carried by each
medic and/or soldier. Mission constraints will dictate how much fluid
is available on the battlefield.
• When intravascular volume expansion is indicated, Hextend® can
achieve this endpoint faster, with
less fluid, and for a longer time than
Ringers lactate.
Based on these assumptions, the Army
Medical Department’s (AMEDD’s) new
algorithm for fluid resuscitation76 is as
follows:
ii. After hemorrhage is controlled to the extent possible, obtain IV access and
start 500 mL Hextend®.
1) Superficial wounds (>50% of injured) - No immediate IV access or
iii. If the casualty’s mental
status improves and a pal-
17
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
casualties should be evacuated at a time that is tactically judicious.
pable radial pulse returns,
stop IV infusion, maintain
saline lock, and observe for
changes in vital signs.
Transient and nonresponders are most likely
continuing to bleed. They
need rapid evacuation and
surgical intervention as
soon as tactically feasible. If
rapid evacuation is not possible, the medic may need to
triage his attention, equipment and supplies, to other
casualties as determined by
the tactical situation. No
more than 1000 ml of Hextend should be given to any
one casualty.
iv. If no response is seen, give
an additional 500 mL Hextend®. If a positive response is obtained, stop IV
infusion, maintain saline
lock, and check vital signs.
v. Titrating fluids is desirable
but may not be possible
given the tactical situation.
Likewise, the rate of infusion is likely to be difficult
to control. Based on the effective volume of Hextend® vs. Ringers lactate
and coagulation concerns
with increasing amounts of
Hextend®, no more than
1000 mL Hextend® should
be given to any one casualty
(approximately 10mL/kg).
This amount is the intravascular equivalent of 6 L
Ringers lactate. If the casualty is still unresponsive and
without a radial pulse after
1000 mL Hextend®, consideration should be given
to triaging supplies and attention to more salvageable
casualties.
(3) Head injuries impose special
considerations. Hypotension
(systolic blood pressure
[SBP] < 90 mmHg) and hypoxia (SpO2 <90%) are
known to exacerbate secondary brain injury. Both are
exceedingly difficult to control in the initial phases of
combat casualty care. Given
current recommendations on
the care of head injuries, we
cannot at this time recommend hypotensive resuscitation, as outlined above, for
the soldier with obvious head
injuries. Should the combat
situation allow for continuous
individual patient attention,
the medic can attempt to keep
SBP > 90mmHg via external
blood pressure monitoring
and evacuate the casualty to
the next higher level of care
as soon as possible. The impasse for the forward-area
vi. Based on response to fluids,
casualties will separate
themselves into responders,
transient responders, and
non-responders.
Responders: Casualties with
a sustained response to fluids probably have had a significant blood loss but have
stopped bleeding. These
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
medic is obvious and will
have to be addressed as
thinking and research on
these issues progress
cians found it equally efficacious. It is
recorded in the proceedings of The
Board for the Study of the Severely
Wounded that,
The…statement of the Committee on
Transfusions…that blood plasma is
approximately as effective in the
treatment of hemorrhagic shock as
is whole blood, appears to have
found origin in the conclusions
drawn from laboratory experiments
that were purposely designed so that
the number of variables could be
rigidly limited. Transference of
these conclusions to a situation that
introduced a number of additional
variables [e.g.. combat casualties]
was an error of human reasoning.78(p.5-7)
Crystalloids versus Colloids
Although recently overshadowed by the
discussion about whether IV fluids have
any value at all in the prehospital setting
(see above), the long-standing dispute
over whether crystalloids or colloids are
the better resuscitation fluid remains.
The origins of this dispute go back to
Ernest H. Starling and William M. Bayliss, two British physiologists, in the
early 1900s.49 Bayliss concluded that the
reason saline was generally ineffective
in resuscitating patients in hemorrhagic
shock was because most of it leaked out
of the intravascular space; this he had
clearly demonstrated in his laboratory.
Following World War II, DeBakey and
Carter were quoted by Henry Beecher as
having said the following about plasma:
A modern discussion of the physiology
of crystalloid and colloidal solutions can
be found in Prough’s article on the subject in 1996.75 Bayliss did the first experiments with colloidal solutions and it
was he who introduced into clinical
practice the first colloidal resuscitation
fluid, a solution of 6−7% gum acacia in
normal saline.76 James Hogan, an
American contemporary of Bayliss, advocated, instead of gum acacia, the use
of gelatin solution for the treatment of
shock.77 Bayliss strongly advocated the
use of his new colloidal solution for the
treatment of patients in hemorrhagic
shock during and after World War I.
Gum acacia, however, was not widely
accepted by military surgeons because
they were unimpressed with its efficacy
for this indication.
Unfortunately, the early enthusiasm
that accompanied this development
[use of plasma to treat hemorrhagic
shock] was so forceful that it pushed
aside sound clinical judgment and
led to the widespread misconception
that plasma could be used as an effective and complete physiologic
substitute for whole blood in the
management of shock in the seriously wounded….With increasing
experience in the treatment of shock,
it became more and more evident
that plasma could not be used as a
complete substitute for whole blood.
56
It is perhaps because of the lack of any
clearly definitive evidence of superiority
of crystalloids over colloids (or viceversa) that the argument as to which is
most effective has been sustained so
long and has occasionally generated
Plasma was introduced during World
War II for the treatment of shock and
was widely used, although not all physi-
19
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
such heat (without much light). Proponents of either position can cite numerous supporting studies. What is known
is that when the efficacy of these fluids
in reducing death from hemorrhagic
shock in trauma patients is assessed,
there is no clear winner and the available evidence tilts toward crystalloids as
being slightly more efficacious.
differences in extravascular lung water
induced by either fluid and concluded
that either one is suitable for treating
simple hemorrhagic shock without undue concern regarding pulmonary
edema. “[I]n the absence of hypervolemia,” stated Prough, “there appears to be no clinical difference in
pulmonary function after administration
of crystalloid or colloid solutions.”75
In 1989, Velanovich conducted a metaanalysis of eight randomized prospective trials comparing crystalloid with
colloid resuscitation. In this analysis
patients resuscitated with crystalloids
had an overall 5.7% relative reduction in
mortality with a 12.3% reduction among
patients in trauma trials.79 A decade
later, Choi et al. conducted an extensive
systematic review of the effects of isotonic crystalloids compared with colloids in fluid resuscitation but found no
overall difference in mortality, pulmonary edema, or length of stay between
groups.80 Although a trend suggestive of
lower mortality in favor of crystalloids
emerged, it was not statistically significant. When the trauma subgroup was
analyzed separately, crystalloid resuscitation was associated with lower mortality than colloid resuscitation 79. Choi et
al. cautioned that these results should be
carefully interpreted and should be used
primarily to direct further inquiry. The
authors concluded that although inference can be drawn that crystalloids are
superior to colloids in resuscitating
trauma victims the data were not conclusive enough to suggest abandoning
colloid administration in practice. In
closing they said, “Larger well-designed
randomized trials are needed to achieve
sufficient power to detect potentially
small differences in treatment effects if
they truly exist.”
One area of controversy remains regarding the question of crystalloids versus
colloids and that is in the situation of
closed head injury. Which of these fluids is more likely to increase intracranial
pressure? Sodium does not freely traverse the blood-brain barrier so it exerts
an osmotic pressure across this barrier.
For this reason an acute reduction of
serum sodium will decrease plasma osmolality thereby increasing the water
content of the brain. The converse is the
case if there is an acute increase in serum sodium.
For some time colloidal solutions were
thought to increase intracranial pressure
less than crystalloid solutions because
they do not cross the blood-brain barrier.
Prough, however, points out that, “In
fact, the choice of fluids (crystalloids or
colloids) for gradual (nonresuscitative)
rates of fluid infusion exerts remarkably
little effect on cerebral edema after experimental head trauma.”75 What has
been shown to affect brain water content
in the setting of fluid resuscitation following closed head injury is the sodium
concentration of the resuscitation fluid.
Serum sodium concentration, rather than
oncotic pressure has the greatest effect
on intracranial pressure.81-84 A general
discussion regarding hypertonic saline
for resuscitation of hemorrhagic shock
and the effect of hypertonic fluid resuscitation on brain injured trauma victims
follows in the next section.
Other studies have reached similar conclusions. Prough found no major clinical
20
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Clifford C. Cloonan, MD
Circulation
Because there is no conclusive evidence
that colloids are superior to crystalloids
in terms of reducing mortality from
hemorrhagic shock and, given their significantly greater cost and, in some instances associated complications, a recommendation that favors crystalloids
over colloids for resuscitation seems
quite reasonable. On the other hand, because colloids do tend to remain intravascular, an equivalent expansion of
the intravascular space can be achieved
with a smaller volume of colloid than
crystalloid solution.
was only temporarily effective in shock
and hemorrhage and that the ‘internal
transfusion’ accomplished by hypertonic
salt solution, which withdrew fluid from
the tissues and thus increased the blood
volume, was equally ineffective.”86(p.8)
As noted in the preceding discussion,
hypertonic saline solutions have been
shown to reduce or at least prevent brain
swelling in patients with closed head
injury who receive fluid resuscitation.87,
88
It has been suggested that an ideal alternative to crystalloid and colloid fluids
would be inexpensive, produce minimal
edema, and effectively resuscitate patients in shock. Hypertonic saline, particularly if combined with a colloid, appears to have some of these characteristics. A number of studies have shown
that 7.5% hypertonic saline, in relatively
small volumes, is an effective resuscitation fluid for patients in hemorrhagic
shock.89-95 Some animal studies have
shown that the beneficial effects of hyptertonic saline alone are not sustained,
but when combined with a colloid they
are longer lasting.75, 96, 97
Pollack in his review of prehospital fluid
resuscitation of the trauma patient, noted
that, “A standard 1-L plastic bag of
normal saline measures approximately
2744 cm3 and weighs 1.1 kg.”85. This
led him to comment, regarding crystalloid resuscitation, “this mode of treatment therefore can become physically
burdensome on the battlefield to a medic
with a limited capacity…for carrying
resuscitative equipment.” Thus weight
alone may recommend colloids in instances where combat medics have to
carry IV fluids on their backs – perhaps.
The literature supports the assertion that
hypertonic saline solutions are safe. Although hypertonic saline administration
may result in serum sodium levels as
high as 155 mEq/L patients seem to tolerate acute increases without harm and
central pontine myelinolysis has not
been observed in clinical trials of hypertonic resuscitation.75
Hypertonic Saline
Hypertonic Saline Dextran
Hypertonic saline resuscitation fluids,
alone or combined with a colloid, have
recently re-energized the discussion regarding which non-blood solution is
most effective for resuscitating patients
in hemorrhagic shock. Actually this issue is not new. Even before the entry of
the United States into World War I “…it
was realized that the injection of physiologic salt solution or Ringers lactate
Morbidity and Mortality Associated
with Fluid Resuscitation
By far the most important study endpoint of interest for those involved in
treating combat casualties is mortality.
The main question about any resuscita21
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Clifford C. Cloonan, MD
Circulation
tion fluid is not, “Does it improve specific physiologic parameters such as
blood pressure?” but “Does it decrease
mortality in patients in hemorrhagic
shock?” Unfortunately there is little supporting evidence for the effect on mortality of any of the current resuscitation
fluids including hypertonic saline.
in patients with concomitant head injury, is warranted.
In assessing the efficacy of any of these
resuscitation fluids it is important to differentiate between controlled hemorrhagic shock, where the bleeding has
stopped or been made to stop, and uncontrolled hemorrhagic shock, where
bleeding is ongoing. Gross et al. found
that hypertonic saline used to treat controlled hemorrhagic shock increases
blood pressure and cardiac output but
when used to treat uncontrolled hemorrhagic shock causes hemodynamic deterioration and increases both bleeding
and mortality.98, 99
Hypertonic Saline Dextran (HSD or
more specifically 7.5% sodium chloride
in 6% Dextran70) has been advocated as
an ideal combat resuscitation fluid because several studies have shown that it
increases myocardial contractility and
improves redistribution of fluid from the
extravascular to the vascular compartment and because considerably smaller
volumes are needed to restore intravascular volume. One of the few human
trials to examine the effect of hypertonic
resuscitation on mortality was a 1991
prospective multi-center study that
compared outcomes of trauma patients
treated with normal saline with those
treated with hypertonic saline dextran.91
Both groups received equal volumes of
fluid in the prehospital phase followed
by standard isotonic infusions in the
emergency department. Unfortunately
there was no control group (i.e., no
group that did not receive fluids) so a
comparison of fluid vs. non-fluid resuscitation was not possible in this study.
Although patients receiving hypertonic
saline dextran had higher systemic blood
pressures than the normal saline group
on emergency department arrival there
was no significant difference in overall
mortality between the two groups at 24
hours. Further, there were no clinically
significant complications of hypernatremia or dextran-related allergic reactions among patients receiving hypertonic saline dextran. The authors concluded that hypertonic saline dextran is
safe, although further study, especially
In 1995 Krausz noted that, in several
clinical studies in which hypertonic saline dextran or hypertonic saline alone
was used to treat trauma patients, mortality was not decreased.100 Previously
he had noted that the early administration of hypertonic saline in uncontrolled
hemorrhage actually increases mortality.101 When hypertonic saline was used
to treat trauma patients with a Glasgow
Coma Scale (GCS) score <8 (suggesting
head injury) Krausz noted a small decrease in mortality; that decrease, however, was not statistically significant.
Based on his review of the studies available at that time (mid-1990s) Kraus
concluded that, “The efficacy of [hypertonic saline] has not clearly been established in clinical trials…Further human
trials are required to better define the
patient population that would benefit
most from the prehospital administration
of [hypertonic saline].”100
Hypertonic saline has also been recommended to resuscitate burn victims (see
below for a complete discussion of fluid
resuscitation of burn victims at or near
the point of wounding). A prospective,
double-blinded controlled animal study
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Clifford C. Cloonan, MD
Circulation
was conducted by Guha et al. to assess
the fluid balance and hemodynamic effects of Ringers lactate, hypertonic saline, 6% hetastarch, and hypertonic saline dextran on animals with large body
surface area burns.102 This study concluded that, “Net volume loading can be
reduced markedly by initial resuscitation
of large body surface area burn injury
using a colloid (hetastarch), and can be
further reduced by use of hypertonic
saline colloid.” Each of the test fluids
was effective at resuscitation, although
more rapid resuscitation was achieved
with hypertonic saline dextran; all fluids
were effective within one hour. There
were, however, large, significant differences, in the amount of fluid infused. In
the first 8 hrs after burn, 10 mL/kg of
hetastarch reduced the net fluid balance
by 48%, and 10 mL/kg of hypertonic
saline dextran reduced net infused volume by 74% compared with lactated
Ringers solution. The authors concluded
that the volume-sparing effects of hetastarch and hypertonic saline dextran must
be tested and confirmed in longer-term
studies before being considered clinically important.102
(see discussion below on hypovolemic
shock due to burn injury).
Historically brain-injured trauma patients have been treated differently than
those without brain injury. In the past,
fluid restriction was recommended for
brain injured patients but today this approach is recognized to cause variations
in volume status and this may lead to
tissue perfusion deficits. Because cerebral ischemia is one of the major causes
of secondary brain injury the current
focus is on aggressive maintenance of
cerebral perfusion pressure (CPP). In
severe head trauma maintenance of CPP
at > 80 mm Hg has an associated mortality of 35−40%. Each additional 10mm Hg decrease in CPP is associated
with a 20% increase in mortality. Increasing the CPP through fluid resuscitation appears to improve morbidity and
mortality.65
Patients with a combination of primary
blast injury burn injury, and penetrating
trauma present an especially unique
challenge, both in terms of early diagnosis and approach to fluid resuscitation. It
is difficult for even experienced professional health care providers, much less
medics or corpsmen, to ascertain
whether a casualty has sustained a significant primary blast injury so tailoring
a specific point-of-wounding resuscitation protocol for these patients is problematic.
Resuscitation Fluids and
Endpoints for Different Types of
Trauma
No single resuscitation fluid or resuscitation protocol is ideal for every type of
trauma. Patients with controlled hemorrhage differ from those with uncontrolled hemorrhage103, those with penetrating injury are different from those
with blunt injury; those with shock and
closed head trauma are different from
those in shock without head injury; and
patients in hypovolemic shock from
hemorrhage are different from those in
hypovolemic shock from burn injury
Casualties with significant burn injuries
should receive early and relatively aggressive fluid resuscitation (see discussion below on hypovolemic shock due
to burn injury) but those with primary
blast injury of the lungs should be volume resuscitated with caution because
they are likely to develop pulmonary
edema if fluid resuscitation is too aggressive. Because of this risk Yancy
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Clifford C. Cloonan, MD
Circulation
Phillips and Joan Zajtchuk, in their
Textbook of Military Medicine chapter
on the management of primary blast injury, recommend that, “Because the
transudation of hypooncotic fluid is
more likely in an injured lung, medical
personnel should consider replacing the
[primary blast injured] casualty’s lost
fluids with blood or a colloid solution
rather than with a crystalloid solution.”104(p.303) Although this seems to be
a reasonable recommendation, no studies show that colloids (or blood) are any
less likely than crystalloids to lead to
pulmonary edema in patients with blast
injury to the lung.105
Further complicating the question regarding what is the ideal combat fluid
resuscitation fluid is the fact that IV fluids are not just used for the treatment of
combat trauma but are more commonly
used by medics to treat dehydration
from a variety of causes (heat injury,
diarrhea, vomiting, etc). The fact that
combat casualties, unlike civilian trauma
patients, may be significantly dehydrated at the time of wounding should
also be taken into consideration when
selecting the most appropriate resuscitation fluid.107 Whatever resuscitation
fluid is selected must, therefore, be not
only safe and effective in the treatment
of combat trauma, but must also be safe
and effective when used to treat other,
more common, conditions.
Difficulties notwithstanding, it seems
likely that each of these situations would
probably best be treated with a unique
fluid resuscitation protocol. Recently,
Pepe and Eckstein commented that,
“Evolving experience, both empiric and
scientific, has demonstrated that the best
treatment for ‘the trauma patient’ requires discrimination between the
mechanism of injury, the location of
anatomic involvement, and the extent, or
‘staging,’ of that specific process.”106
Route/Means of Intravenous
Access
Although there is some controversy
about the value of fluid resuscitation in
the field for combat casualties, there is
general agreement that it is valuable to
establish vascular access at or near the
point of wounding. Even if IV fluids are
not required early intravascular access is
still important for the following reasons:
On the battlefield, however, where there
is an omnipresent threat of injury and
death to both combat medic and patient,
the medic does not have the time or capacity to differentiate among groups of
patients, apply a different treatment for
each, and/or carry several types of resuscitation fluids. Good data is needed
to support the selection of a single resuscitation fluid and protocol that can be
applied to all combat trauma victims.
Because most combat casualties suffer
primarily from hemorrhage caused by
penetrating injury, without associated
closed head injury, the fluid and resuscitation strategy that is most effective for
this condition is likely the most appropriate choice.
1) Fluids and/or blood must often
be given at the medical treatment facility in conjunction
with hemorrhage control, and it
is usually easier and faster to
gain IV access in patients who
are not volume depleted.
2) IV access is often necessary for
purposes other than fluid administration, e.g., administration
of analgesia or antibiotics.
Adequate analgesia is best achieved by
titrating intravenous morphine to the
level of pain, thereby minimizing both
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
patient discomfort and risk of opiate
overdose (if morphine is given IM, especially to hypotensive and/or hypothermic casualties it is poorly absorbed
from the muscle leading to repeated dosing and the risk of delayed onset of opiate overdose).
3) Inadequate control of the rate of
fluid administration [vehicle
evacuation in the forward battle
areas is almost always accomplished without medical attendants using tactical, not medical, vehicles].
Studies by Spaite et al. have shown that
civilian prehospital care providers can
obtain IV access without significantly
delaying evacuation, especially if access
is gained during evacuation108, 109 near
the point-of-wounding access to the intravascular space is generally obtained
by direct venous cannulation, usually in
the upper extremities, and often in the
antecubital fossa. Cannulation should
always be obtained with a short 18gauge (or larger) catheter so that large
volumes of fluids and/or blood can be
administered later if necessary.110-112 As
Poiseuille’s equation [Flow = ΔP π r 4 /
8 η l] states flow through a pipe (e.g. IV
catheter) is directly proportional to the
radius but inversely proportional to the
length of the pipe. While the diameter of
an IV catheter is by far the most important in terms of rate of flow a catheter of
one inch length will have twice the flow
rate of a two inch catheter with a similar
diameter.
In summary, the average casualty who
has had an IV line inserted in the field is
unlikely to arrive at a medical treatment
facility with a functional line, much less
having received a controlled rate of fluid
delivery. This is not as much of a problem as it might seem because, as discussed above, for the average combat
casualty there is no evidence that volume resuscitation in the field improves
survival. Under current guidance for
combat medics if fluids are not to be
administered, IV access can be obtained
using a saline lock (see above, point-ofwounding fluid resuscitation guidelines). Without a line and a bag of IV
fluids to be protected a saline lock is
much more likely to remain functional
during evacuation.
Another option is to obtain intraosseous
access. In a recent review, Dubick and
Holcomb discuss the safety, efficacy,
insertion times, and flow rates associated with intraosseous vascular access.113 Although intraosseous infusion
has been used for many years in pediatric resuscitation114, this method has recently been rediscovered as a means for
prehospital fluid resuscitation in
adults.115, 116 In 1922, Drinker et al.
demonstrated that red blood cells could
be infused into the bloodstream through
the intraosseous route.117 In the early
1930s, this technique was demonstrated
to be effective in humans 118, 119 and a
few years later it was brought to the battlefield in World War II. Turkel, in
1956, commented that “Many of our
fighters [in WWII]…were saved by the
Even if clinically indicated fluid administration in the field can be problematic
because care providers must then manage not only the casualty but the IV fluids and lines as well. IV management
during combat/evacuation can lead to:
1) An unfortunate shift in the focus
of care from the patient to the
IV,
2) Difficulty ensuring that the IV
line is not pulled out, and, at the
very least
25
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Clifford C. Cloonan, MD
Circulation
intrasternal transfusion method administered to them by enlisted nonmedical but
medically trained men.120
ing intravenous and intraosseous routes
of administration of hypertonic saline
dextran. Chavez-Negrete et al. compared intravenous-infused and intraosseous-infused hypertonic saline dextran
in patients with gastrointestinal hemorrhage.126 Sternal intraosseous and intravenous hypertonic saline dextran were
equally effective and there was no difference between the two groups in terms
of blood pressure response. No complications were noted in either group.
Today the two main routes of intraosseous access in adults are the medial malleolus and the sternum. The intramedullary space of the medial malleolus is
somewhat difficult to access because of
relatively thick overlying cortical bone
but a device known as the bone injection
gun [B.I.G.®] eliminates this problem by
firing a spring-loaded hollow dart
through the cortex to the correct
depth.121, 122
The intraosseous route of fluid administration is generally considered safe. In
1947 Heinild et al. reviewed nearly
1,000 pediatric intraosseous infusions
and found few complications.127 More
recently Orlowski et al. assessed the
risks of intraosseous fluid resuscitationinduced fat and bone marrow emboli
and found that although emboli did occur they were not clinically significant.128 Other studies and reviews have
confirmed the relative safety of the intraosseous route.129-131
The red bone marrow-containing intramedullary space of the sternum can
be accessed through a flat, relatively
thin bony cortex located just under the
skin. This route is ideal but there is the
potential risk of injury to major underlying vasculature in the mediastinum. A
sternal intraosseous infusion device
[F.A.S.T.®] allows for safe and rapid
placement of an intraosseous needle into
the sternal intramedullary space.123-125
A recent study by Alam et al., however,
has raised some concern about a potential risk associated with intraosseous
infusion of hypertonic saline dextran.132
In this study multiple intraosseous infusions of hypertonic saline dextran to
dehydrated pigs caused severe necrosis
of the tibia. The clinical relevance of
this finding to human trauma patients is
unknown.
With these devices an intraosseous infusion can be safely and reliably started in
less than a minute. Because of relatively
high resistance to flow through the intramedullary space into the intravascular
space, it is not possible to administer
large volumes of fluid rapidly via this
route. It has, however, been previously
pointed out that rapid, large-volume
fluid resuscitation is harmful when
bleeding has not been controlled, so this
is often not an issue.
Any parenteral fluid access site that is
obtained at, or near, the point of wounding must be replaced as soon as a new
site can be established in a clean environment. When access is obtained in a
combat zone, the patient’s risk of developing infectious complications increases.133 During recent combat operations in Afghanistan, several cases of
sepsis were reportedly associated with
Hypertonic saline dextran has been recommended as the preferential intraosseous infusion fluid when volume resuscitation is indicated because of its ability
to rapidly expand the intravascular space
with minimal infused volume. Currently, there is only one study compar-
26
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Clifford C. Cloonan, MD
Circulation
field-started intravenous lines [conversations of author with combat medical
personnel]. Osteomyelitis has been reported following intraosseous infusion134 and is a risk in field-started intraosseous infusions that are left in place
longer than 24 hours.
the Red Cross on prehospital care for
war and mine wounded agreed that any
wounded patient, regardless of wound
type or severity, who had not lost consciousness could be given oral fluids.
No specific guidelines were developed,
however, and the workshop concluded
with the thought that oral rehydration is
a primary area for future research.
When fluid resuscitation is indicated
intraosseous infusion via either the sternal or medial malleolus routes is a reasonable option either as a backup
method to the intravenous route or as a
primary means of access. There are certainly other methods of obtaining access
to the intravascular space but in general
none are appropriate at, or near, the
point of wounding.
135(p.89)
Although there is concern about the potential for aspiration either during
evacuation or surgery, no reliable scientific data confirm that drinking water
actually poses such a risk. In the past
decade or so the long-standing recommendation that there be a long period of
preoperative fasting has been changing,
particularly with regard to water.136-140
The general consensus is that water, in
any quantity, is without risk 2 hours or
more before surgery. There have been
suggestions that even combat casualties
with abdominal wounds can have sips of
water as tolerated. In sum there appears
to be no good evidence to support withholding water from wounded patients
and providing water seems reasonable
from a physiological standpoint.
Oral Rehydration
Oral rehydration of hypovolemic
wounded soldiers should not be overlooked – simple solutions often are. In
alert patients without nausea, or even in
those with mild nausea, a careful oral
rehydration may be reasonable.
Attendees of a 2001 workshop organized by the International Committee of
Transfusion Near the Point of Wounding
hemolytic reactions; immediate ABO
and delayed non-ABO reactions; allergic and anaphylactoid reactions; febrile
reactions; noncardiogenic pulmonary
edema; hypothermia; citrate toxicity;
acid-base imbalance; hyperkalemia or
hypokalemia; bacterial contamination;
and transfusion-transmitted diseases
such as human immunodeficiency virus
(HIV), hepatitis, cytomegalovirus, West
Nile virus, and Creutzfeldt-Jakob disease to name a few.66
Since prior to World War I blood has
been recognized as the ideal resuscitation fluid for patients in hemorrhagic
shock. The reason other fluids have, at
times, assumed a leading role in the resuscitation of combat casualties, particularly far forward, is because of the problems that are associated with administration of blood on the battlefield. Even
with modern technology administration
of blood and blood products is risky and
logistically difficult. The risks and complications of transfusion therapy include
27
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Clifford C. Cloonan, MD
Circulation
In a recent review of blood transfusion
medicine avoidable transfusion errors
were deemed an important, if uncommon, cause of iatrogenic death and injury in U.S. hospitals.141 Given the chaotic circumstances that often prevail in
combat, it is probable that the rate of
such errors is even higher when transfusions occur on the battlefield.
transfusion and blood transfusions were
begun in 5% (29 of 543) of patients who
required an IV; 124 units of blood were
administered in transit.145
The decision to administer blood far
forward in this particular military operation was probably made because, unlike
previous Arab-Israeli wars in which
evacuation times to fixed hospitals were
relatively short, in the Lebanon operation, evacuation times were long. As
discussed in a 1999 study by Barkana et
al., the IDF Medical Corps has been using blood in prehospital resuscitation of
trauma patients since the 1980s.146 In the
IDF experience, time from wounding to
hospital admission almost always exceeds 1 hour, and often runs 2–3 hours.
The IDF uses Rh-positive type O packed
red blood cells that are supplied by the
central civilian blood bank and are kept
in a special field refrigerator. The blood
is maintained by military medical units
whose members do not have any “expert” training in the maintenance of
blood products. Before use, 250 mL saline is added to facilitate administration.
IDF forces are somewhat unique in that
physicians are stationed very far forward, often at or near the point of
wounding. It is the physician who determines whether or not to administer
blood, based upon ATLS guidelines.
Fatal misidentification errors in the
United States are estimated to occur in 1
in 600,000 to 1 in 800,000 transfusions
and non-fatal errors occur in 1 in 12,000
to 1 in 19,000 cases.142, 143 An error incidence of 335 per 5.5 million units of red
cells transfused is reported from the
United Kingdom with transfusion of an
incorrect blood component accounting
for almost 70% of adverse events between 1999 and 2000.144 This study also
reported 97 cases of ABO blood group
incompatibility that led to immediate
major complications in 29 patients and
death in 4 patients.
Every medical intervention, including
blood and blood product administration,
has risks. The basic question is, “When
the risks are balanced against the benefits, does the equation favor forward
administration of blood to combat casualties at or near the point of wounding?”
The Israel Defense Forces (IDF) would
answer in the affirmative. Although it
was generally not Israeli policy to supply blood to forward area medical units,
an exception was made during the Israeli incursion into Lebanon in 1982,
where heavy casualties and difficult
evacuations associated with urban combat (i.e., in Beirut) were anticipated.144
During this operation, 85% of Israeli
casualties were airlifted from the battle
zone and 95% received some treatment
before air evacuation (almost always
this included having an IV started).
Every Israeli helicopter carried blood for
The Barkana et al. study offered no conclusions about the efficacy of this practice because no comparison was made
between casualties receiving prehospital
blood with those not receiving blood.146
The authors were able to conclude,
based on their experience, that (1) blood
can be administered safely at or near the
point of wounding by individuals not
specially trained or experienced in blood
administration and (2) prehospital administration of O-positive packed red
28
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Clifford C. Cloonan, MD
Circulation
blood cells is efficacious and indicated
in selected patients.146
“dangerous,” this was not the case for
blood transfusion which “…may be
given in the Classification Posts [and
although]…blood may drive out
blood…[if] the patient is not long in
reaching the operating theatre, the net
result is some gain.54(p.189)
There are four major reasons to transfuse blood or blood components into a
hemorrhaging patient:
1. To improve systemic oxygen
transport
2. To restore critical red cell mass
3. To correct bleeding caused by dilutional thrombocytopenia, platelet dysfunction, or pathologic
platelet consumption
4. To correct bleeding caused by a
factor deficiency or pathologic
consumption of coagulation proteins.
During World War II, the British established Field Transfusion Units, the
smallest units in the British Army.
These units were entirely self-contained,
were fully equipped for transfusion in
the field, and consisted of an officer and
three enlisted men, one of whom drove
the truck and was responsible for the
operation of the refrigerator. These units
were attached wherever they were most
needed during a campaign, usually operating at field surgical units, but also at
field dressing stations and casualty
clearing stations.149
In short, the goals of transfusion therapy
are to maintain physiologic support of
the circulation and oxygen transport
while avoiding the deficiencies of hemostatic factors or other physiologic
deficits.65
Today, for reasons that are not entirely
clear, blood is no longer routinely administered forward of units with surgical
capability. This has not always been the
case. During the Spanish Civil War, “In
some classification posts [read Battalion
Aid Station] blood transfusions were
given to badly shocked men – usually
with conserved blood but sometimes by
direct transfusion.”54(p.24)
Although it is not possible to comment
on the specific benefit gained by the
administration of blood forward of units
with surgical capability, it is clear that
overall blood administration was credited with saving a large number of lives
in World War II and Korea. “Prompt
and liberal use of whole blood” was
deemed responsible for saving the lives
of innumerable casualties in World War
II and the Korean War and is considered
“one of the great pioneering achievements of World War II.149
It was during the Spanish Civil War that
Dr. Norman Bethune established the
first known mobile blood bank unit; it
successfully delivered whole blood to
casualty stations and provided “transfusions at the front while the fighting was
in progress.”147(p.124)148 It was also observed during this war that, although the
“administration of large quantities of
intravenous saline or glucose [or solutions containing gum Arabic]” was
COL Edward D. Churchill, the Consultant in Surgery, Fifth U.S. Army in
World War II, in his study of whole
blood and plasma and their relative role
in the resuscitation of combat casualties,
concluded that, “…whole blood [is] the
agent of choice in the resuscitation of
the great majority of battle casualties”
and that, “…whole blood [is] the only
therapeutic agent that [will] prepare
seriously wounded casualties for the
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Clifford C. Cloonan, MD
Circulation
low hemoglobin level, transfusion, and
mortality. The authors recommended
further study of transfusion in ICU patients, as well as exploration of alternatives to transfusion.
surgery necessary to save life and
limb.”149(p.57)
Following World War II, Henry K.
Beecher noted that, “Too much preoccupation in the clinical treatment of patients with the unsolved problems of
shock can have the indirect but very
closely associated result of leaving the
physician without access to the therapy
well proved to be effective in the treatment of shock: blood as needed.”55 He
also observed that, “The shock we saw
was caused by blood loss (or loss of
fractions of the blood). It was cured by
blood administration.”55
Multiple components contained in
stored blood can increase levels of proinflammatory mediators that may lead to
neutrophil activation and promote the
development of multi-organ failure.152154
The implication of these findings for
combat casualties is unclear. Certainly,
the non-trauma ICU patients in the
above study by Vincent et al. are quite
different from combat casualties.151
There is also a difference between the
effectiveness and side effects of stored
packed red blood cells, whole blood,
and fresh blood.
Regarding the efficacy of blood transfusion in the field, a modern retrospective
chart review by Hall et al. found that
trauma patients who received packed red
blood cells in the field had outcomes
similar to those who did not, despite the
fact that the group who received blood
had significantly worse injuries (in particular more serious intra-abdominal
injuries) than the group who did not receive blood.150 From these results, the
authors concluded that early administration of blood may be of value, and recommended further study.
During World War II, it was recommended that all transfusions be given
with fresh blood in order to “make up
for the lack of standardized equipment
and the shortage of shipping space …in
evacuation hospitals.” This proposal was
incorporated into Circular Letter No.
108, Office of the Surgeon General,
U.S. Army, dated 27 May 1943, which
stated that, “…fresh whole blood
[should be administered] in general
hospitals in oversea[s] theaters within 4
hours after it had been collected and for
the transfusion of stored blood [it
should be] collected…and used within 7
hours...”149(p.180) Also during World War
II, COL Elliot Cutler recommended,
“transfusion of severely wounded casualties with blood secured from lightly
wounded casualties.”149(p.192)
Despite overwhelming support for early
blood transfusion by military surgeons
with considerable experience in resuscitating combat casualties, there have
been recent studies on blood transfusion
that should give pause. Vincent et al., in
a recent, extensive review of blood
transfusion in critically ill patients,
found a dose-response relationship between number of red blood cells infused
and mortality.151 All other variables
being equal, receipt of a blood transfusion increased mortality risk by a factor
of 1.4. This study illustrates the associations between transfusion and diminished organ function as well as between
Clearly fresh whole blood, and even
stored whole blood, is different from
packed red blood cells. These differences could certainly account, at least in
part, for the apparent difference between
the findings of Vincent et al. in ICU pa-
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Clifford C. Cloonan, MD
Circulation
In a patient with a chest wound, this can
be done by collecting blood directly
from a thoracostomy tube, using a suction device, into a citrate-containing
bag. The blood can then be directly reinfused through a macroaggregate filter.
Another method of blood collection involves the use of a cell saver unit that
collects blood into a system that
tients and the observed effects of whole
blood given to combat casualties in
World War II.
COL John B. Holcomb, an army surgeon, commented very favorably on the
beneficial effects of whole blood transfusions given to exsanguinating combat
casualties in Mogadishu, Somalia in
September and October 1993. He said
that whole blood had a nearly “miraculous effect” when given to patients who
were exsanguinating.155 [Holcomb JB,
Colonel, US Army. Personal communication, August 2003]
•
•
For at least the past four decades, the
general US military policy has been to
use packed red blood cells for resuscitating combat casualties both because
packed red blood cells are believed to be
as effective as whole blood and because
they have logistical advantages. Despite
this stated policy, fresh whole blood has,
in fact, been used by US Forces in every
conflict with significant casualties since
World War II, including Operation Iraqi
Freedom; Army doctrine is being
changed to reflect this reality.156 In
short, the experience of military surgeons in the 20th Century supports the
use of whole blood in resuscitation of
combat casualties.
Includes an anticoagulant and
Uses centrifugation and a washing mechanism to provide
washed red blood cells for infusion.65
Autotransfusion was effectively used to
treat combat casualties with chest
wounds during the war in Bosnia in
1992. Jevtic et al. described 19 cases of
autotransfusion of blood collected from
chest tubes inserted into 29 casualties
with penetrating chest trauma.157 The
average quantity of returned blood delivered was 1,500 mL but in two patients, both of whom survived, ≥ 4,000
mL autotransfused blood was administered.
Although autotransfusion avoids a number of the potential risks of using donor
blood (e.g., viral infection) there are
several potential complications that are
more common in autotransfusion. These
include coagulopathy caused by excessive anticoagulant and disseminated intravascular coagulation caused by administration of activated products of
coagulation and fibrinolysis. Typically,
these complications are seen when
>1500 mL shed blood is reinfused.
Autologous Transfusion
One way to avoid many of the risks of
blood transfusion is to use the patient’s
own blood. There are two ways to do
this:
1. Collect the blood in advance of
the need (not really an option for
combat casualties) and
2. Return the patient’s own lost
blood back to the circulatory system through autotransfusion.
Autotransfusion of blood from the abdominal cavity can be used in the operating room, but this route of blood administration is not an option in the prehospital environment so is not discussed
here.65 Based upon the above observa-
31
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
tions, consideration should be given to
increasing the emphasis at the Battalion
Aid Station on autotransfusion of blood
recovered from the chest via a thoracostomy tube.
oxygen affinity (with limited off-loading
of oxygen at the cellular level), short
intravascular half-life, and renal toxicity. Development in the 1980s of modified polymerized hemoglobin solutions
was the start of present-day research
efforts in this area. These new solutions
are more stable, have better oxygen delivery characteristics, and have fewer
side effects; although some problems
remain.
Blood Substitutes
One challenge of the modern battlefield
is the high degree of troop dispersion
and the resulting long evacuation distances and times. In recent combat operations, the time from point of wounding to surgery has approached 24 hours.
This means that wounded soldiers will
have to be sustained much longer before
they receive surgery. Ideally, part of this
sustainment effort would be accomplished with blood administration, preferably fresh whole blood; but logistical,
technical, and provider skill level issues
preclude this being a viable option.
Six companies currently have hemoglobin-based blood substitutes (Baxter [HemAssist™], Hemosol [Hemolink™, hemoglobin raffimer], Northfield [PolyHeme®], Somatogen [Optro™], Sangart
[Hemospan™], and BioPure [Hemopure®, HBOC-201, or hemoglobin
glutamer-250)]) that have completed
patient safety studies, and some have
begun efficacy trials. None of these
products requires type and cross-match,
all have relatively short half-lives (about
24 hours) and fairly long shelf lives, and
none appears to be associated with any
risk for transmission of disease. There
is, however, some concern about the
possibility of prion transmission by
products made from bovine hemoglobin.
Biopure’s Hemopure® is currently approved for some indications in human
patients in South Africa, and Phase III
testing for US Food and Drug Administration (FDA) approval is ongoing.
One option that is aggressively being
pursued is the development and fielding
of an oxygen-carrying resuscitation
fluid. The search for a safe and effective
oxygen-carrying resuscitation fluid has
become the Holy Grail of military medicine. Millions of dollars have been spent
over the past 35 years in hopes of finding a safe and efficacious blood substitute. The search actually began in the
early 1600s, almost soon as it was discovered that blood circulated in the
body and was vital to life.158 In 1665,
Christopher Wren tried using wine as a
blood substitute, without beneficial effect. The beginnings of the modern
search for an effective blood substitute
began in the 1930’s with Amberson,
who infused stroma-free hemoglobin.159
Two crosslinked hemoglobin solutions
are currently in production: pyridoxylated hemoglobin (PLP-Hb) and diacetylated crosslinked hemoglobin (DCLHb),
and other products are in development.
PLP-Hb is a dimer and DCLHb is a purified human tetrameric hemoglobin
molecule. In a number of these products
hemoglobin is encapsulated in liposomes; these liposome-encapsulated
hemoglobins are stable during storage
and have a plasma half-life of 4–20
The greatest efforts in this area began in
the early 1970s, with the work of
Rabiner et al 160 and Savitsky et al.161
Unfortunately, despite some success,
there were many problems, such as high
32
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
this solution had a considerably lower
30-day mortality (25%) compared with
an historical control of patients who refused blood transfusion for religious
reasons (64.5%).164 Final (Phase III)
studies are currently underway evaluating this oxygen-carrying blood substitute in the prehospital treatment of
trauma patients. If the results of this trial
are favorable, this solution and/or others
could have a substantial impact on the
treatment of combat casualties at or near
the point of wounding.
hours without associated renal toxicity
or antigenicity.158
Hemoglobin used in these solutions
comes from (1) human red blood cells
(expired donated blood), (2) bovine red
blood cells, or (3) recombinant hemoglobin sources. All of these hemoglobinbased oxygen-carrying solutions have a
high affinity for oxygen. Indeed, the
problem has not been with these solutions binding oxygen in the lungs but
with releasing that bound oxygen to the
tissues that need it. Another problem
with many of these solutions is that most
have at least some degree of vasopressor
effect secondary to binding nitric oxide
(endothelial-derived relaxing factor). As
noted earlier, increasing blood pressure
when hemorrhage is uncontrolled simply leads to a faster rate of blood loss.
Non-hemoglobin-based oxygen carrying
solutions are also being developed as
possible blood substitutes; most of these
are perfluorocarbon-based. Oxygen and
carbon dioxide are highly soluble in perfluorocarbons, which makes these solutions able to carry oxygen to the tissues
and carbon dioxide back to the lungs. In
comparison to hemoglobin-based oxygen-carrying solutions, perfluorocarbons
are much more effective at unloading
oxygen at the tissue level. Perfluorocarbon emulsion solutions transport oxygen
in a fundamentally different way than do
hemoglobin based solutions. Hemoglobin based solutions exhibit a sigmoidal
oxygen dissociation curve. The oxygen
carrying capacity of perfluorocarbon
emulsions, in contrast, is characterized
by a linear relationship between PO2 and
oxygen content. Thus, sufficient oxygen
delivery can only occur when patients
are breathing 70 to 90% oxygen. Therefore, unlike hemoglobin-based solutions,
in which supranormal levels of oxygen
provide little additional benefit (and
provide little added oxygen delivery to
red blood cells), when perfluorocarbon
emulsion solutions are used, elevated
PO2 such as that achieved with hyperbaric oxygen, is quite beneficial. Unfortunately this property means that perfluorocarbons are likely to be less valuable as a point-of-wounding resuscita-
Although there was much anticipation
that DCLHb would become the first of
several hemoglobin-derived, oxygencarrying blood substitutes to successfully treat hemorrhagic shock, a multicenter trial evaluating the efficacy of
DCLHb was terminated when it became
clear that there was a significant increase in mortality associated with the
use of this solution.162 At 28 days, 46%
of those infused with DCLHb died,
compared to 15% mortality in those infused with saline. The incidence of multiple organ dysfunction was also considerably higher in the DCLHb group, and
the authors concluded that DCLHb was
not effective for fluid resuscitation.
Another hemoglobin-based, oxygen carrying solution, which consists of polymerized tetrameric human hemoglobin, is
currently undergoing final testing and
appears efficacious and safe.163, 164 A
study of this polymerized human hemoglobin solution in a relatively small
number of trauma patients found that
33
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
tion fluid because oxygen, which is
needed to maximize the effectiveness of
these solutions, is generally not available.
maceutical Corp., San Diego), which is
prepared from perfluorooctyl bromide
(C8F17Br) with egg yolk lecithin as the
surfactant. This product, which is compatible with all blood types and has a
shelf life of as long as 2 years, has
moved from Phase II clinical trials to
Phase III trials.170 Preliminary data indicate that use of Oxygent obviates or
minimizes the need for blood, with results being statistically significant to 3weeks post-administration.
Advantages of perfluorocarbons include
the following:
•
•
•
Some of these solutions can be
stored at room temperature
They are relatively cheap to
produce
They are completely free of biological material so they cannot
be contaminated by infectious
agents
Although this, or another, effective
blood substitute may someday be available for administration at or near the
point of wounding, the promise of this
prospect is unlikely to be fulfilled in the
near future. When an efficacious oxygen-carrying blood substitute does become available, it will represent a major
military medicine milestone that will
likely have a significant impact on combat casualty survival.
Because fluorocarbons may unfavorably
alter the reticuloendothelial system by
long-term retention and can lower immunity 165-169 they are coated with substances, such as lecithin, which makes
them soluble and reduces the extent to
which they affect the immune system.
One such agent is the intravascular oxygen carrier, Oxygent™ (Alliance Phar-
Pneumatic Antishock Garment
mechanism of “autotransfusion” of
blood from the lower extremities into
the central circulation. The PASG certainly does raise the blood pressure of
patients in shock, and in animal models
with controlled hemorrhage it prolonged
survival from otherwise fatal exsanguination 171, but it does so not by autotransfusion but by raising total peripheral vascular resistance and increasing
afterload.172, 173 Given that raising blood
pressure in trauma patients with uncontrolled hemorrhage has been shown to
be undesirable since at least the Spanish
Civil War, it should have been a foregone conclusion that the PASG might
actually worsen survival in trauma vic-
The pneumatic antishock garment
(PASG), also known as military antishock trousers (MAST), is a device
that encircles the abdomen and lower
extremities with air bladders that can be
inflated. The concept for this device
originated from the “G” suits worn by
pilots of high-performance aircraft;
these suits inflate during highgravitational-pull maneuvers to prevent
loss of consciousness caused by pooling
of blood in the lower extremities.
The original belief was that this type of
device could be used to treat shock by a
34
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
development of compartment syndrome
in previously normal lower extremities.181-184 Furthermore, even during the
period when its use was recommended,
the PASG was known to be harmful to
patients with closed head injury, thoracic injury, pregnancy, and/or pulmonary edema.
tims with on-going hemorrhage; unfortunately this was not the case.
Until relatively recently, the PASG was
one of the most widely used and moststudied devices in emergency medicine
and prehospital care.174-176 Pneumatic
Antishock Garments (PASGs) were a
mandatory item of equipment on every
ambulance in some states. Today, however, the PASG has developed such a
bad reputation that it is rarely used at all.
In some ways, the PASG is an excellent
case study in why it is important to conduct randomized controlled human trials
of all medical equipment, medical procedures, and pharmaceuticals before
introducing them into widespread use.
In the short span of about 25 years, the
PASG went from invention, to widespread use, to obscurity.
It should be noted that the Mattox and
Bickell study 179 of the PASG was done
in an urban environment with very short
prehospital transport times. Whether the
results would have been different had
the transport times been longer is unknown, but there is no obvious reason
why they would have been. Despite its
problems, the PASG continues to be
recommended by some [including this
author] to apply compression over large,
soft-tissue injuries in the lower extremities for hemorrhage control (PASGs reduce arterial and venous bleeding beneath the garment by decreasing vessel
wound size, transmural pressure, and
blood flow)174, 176, 184, 185 to stabilize
lower extremity fractures, and to help
stabilize unstable pelvic fractures (see
discussion below on pelvic fracture stabilization). There is some scientific support for these recommendations.185, 186
The limitations of the PASG prompted
McCallum and Rubes in 1996 to suggest
removal of the PASG from ambulances
because of its “low utility and utilization.”187 Although PASGs have, in fact,
been removed from most military medical equipment sets, their utility in helping to control lower extremity hemorrhage and stabilize lower extremity and
pelvic fractures suggest that they should
be kept available for these purposes.
Prehospital medical personnel simply
need to be taught that PASGs should not
be used solely to treat hemorrhagic
shock.
PASG – Pneumatic Antishock Garment, From
Operatiopnal Medicine 2001
Interestingly, it was one of the greatest
early advocates of the PASG, Dr. Ken
Mattox, who ultimately conducted the
studies 177-180 that showed increased
mortality in patients with penetrating
abdominal injuries when the PASG was
used. In patients with large-vessel involvement, survival rates were 49% for
the PASG group and 65% for the control
group. Not only was the PASG shown to
be worse than ineffective, its use was
associated, in some instances, with the
35
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
Hemmorrhage Control
"Hemorrhage, which produces such terror in the bystanders . . . should never unnerve the
surgeon, who requires all of his self possession . . . to cope successfully with this ebbing
away of life."188
lory noted during a conference held at the
end of the Korean War that, “In the case
of lower extremity wounds, which give rise
to the most severe hemorrhage controllable by tourniquet, it has been my observation that too few doctors, much less their
assistants, have a concept of the constricting pressure required about the thigh to
abolish the flow of blood.”190 Prolonged
pressure is physically demanding and prevents whoever is doing it from engaging
in other tasks (like defending himself and
his patient).
Direct Pressure
Hemorrhage control is generally achieved
by the application of direct pressure on the
bleeding site. When possible, this is combined with elevation of the bleeding site
above the level of the heart, which lowers
the pressure at the point of bleeding. Digital pressure applied over proximal arterial
pressure points also helps to control bleeding by lowering the pressure at the bleeding site(s). Performed correctly and, when
possible, simultaneously, these hemorrhage control techniques can control significant, even brisk arterial, hemorrhage.
Although obvious pulsatile hemorrhage
from a severed artery usually catches the
attention of medical personnel and is dealt
with promptly, if not adequately, what is
often underappreciated is that casualties
with large soft-tissues injuries and extensive venous ooze are also at very real risk
of exsanguination -- if not in so dramatic a
fashion.
Until recently there has been no good
method for teaching these techniques to
prehospital medical personnel and so
when treating hemorrhage in combat
casualties, these personnel often apply
insufficient pressure for an insufficient
period of time. Fortunately, there has recently been increased emphasis on hemorrhage control at the 91W Health Care
Specialist Program at the AMEDD Center
& School at Fort Sam Houston, Texas and
this has, in part, been made possible by the
introduction of training devices that simulate realistic hemorrhage.189
During the Korean War, Artz, Sako and
Howard noted that at the 46th Surgical
Hospital there were 20 deaths among 138
severely wounded patients. Of these, 7
(35%) died of uncontrolled hemorrhage, 4
(20%) from uncontrolled postoperative
oozing, and 3 (15%) from uncontrolled
major vessel injury.191 Patients were noted
to have died from persistent oozing from
massive muscle wounds. Persistent bleeding from a scalp wound can also contribute to exsanguination. One death during
recent combat operations in Afghanistan
was attributed to failure to control persistent venous ooze.192
Unfortunately, no matter how well this
task is taught, the circumstances of combat make it unlikely, in many cases, that a
medic/corpsman will be able to apply the
requisite force long enough to achieve
hemorrhage control. Maj. Meredith Mal-
36
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
Whether this device, or any other, will
solve the problem of applying sustained
focused direct pressure on the wound is
unknown, but anything that could accomplish this task while freeing up the
medic/corpsman would be a very useful at
or near the point of wounding.
Sustained application of direct pressure
may be facilitated by a field-expedient
method, that of placing a sandbag inside a
clean cover and putting it directly over the
top of the pressure dressing on the wound.
This is basically what is done in a hospital
setting after an arterial catheterization has
been performed. There are, however, two
problems with this recommendation:
Tourniquets
A tourniquet is a constricting or compressing device that is used to control venous
and arterial circulation to an extremity for
a period of time. The tourniquet has been
recognized as effective at controlling
hemorrhage since at least the time of the
Greeks 194 and it was described briefly in
Roman literature but, perhaps because it
lead to gangrene, it did not come into general clinical use until sometime in the mid1500s when Ambrose Paré is credited with
it’s discovery as a useful medical device
when accompanied by ligature of the
bleeding vessel.194 In 1628, William Harvey, an English surgeon, described the
human circulatory system in detail, thus
paving the way for future technological
developments in hemorrhage control.
1. A sandbag is not always available,
and
2. A fully filled, full-size sandbag may
be too heavy and may disperse pressure over too large an area.
A new product, named the BioHemostat®,
is currently in development, which may
solve both of these problems and may also
be so effective as to negate, in many instances, the need for a tourniquet. Developed in 2001 by a team led by Marcus E.
Carr, MD, PhD at Virginia Commonwealth University, the BioHemostat®
combines a traditional pressure dressing
with an attached bag that is filled with a
water-absorbing polymer that can absorb,
within 3 minutes, up to 1400 times its
weight in blood (or water).193
In 1718, Louis Petit, a French surgeon,
developed a screw device, designed to
apply pressure to specific arterial points in
order to limit bleeding. It is from the
French verb "tourner" (to turn), that Petit
named his device a "tourniquet." Since its
introduction by Paré into clinical practice,
the ligature, or tourniquet, has been a
standard medical item for military surgeons and has remained largely unchanged from its original form. A tourniquet on display at the National Museum of
Civil War Medicine in Frederick, Maryland is remarkably similar to the one that
was, until quite recently, standard Army
issue to medical personnel (it still remains
in the inventory).
When the bag expands, it can apply up to
90 mm Hg direct pressure, and if properly
applied, will exert this force almost directly on the site of bleeding. This exerts a
tourniquet-like effect on the bleeding vessel while allowing collateral vessels to
continue to perfuse distal parts. Expansion
of the polymer is triggered either by absorbed blood or water injected into the
polymer-containing bag to cause immediate expansion. The pressure in the bag is
controllable by the amount of water
added. The addition of a hemostatic agent
to this dressing could further enhance its’
hemostatic properties.
37
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
continues to be true, as Dr. Gray said,
“Blind grouping in the dark” for a bleeding vessel is worse than useless.
Although a properly applied tourniquet is
clearly effective at controlling distal extremity hemorrhage, the liberal use of
tourniquets has long been discouraged
because of their associated risks. Dr.
Julian Chisolm, a senior Confederate surgeon, made the following comments about
tourniquets in his book, Manual of Military Surgery:
It was his experience with tourniquets during the Spanish Civil War that lead Dr.
Douglas Jolly to comment that, “More
limbs and lives are lost at the front from
the improper use of the tourniquet than
are saved by its proper use.”54(p.24) During
World War II, the use of tourniquets
evolved as experience was gained.196(p.427428)
In Volume 1 of Activities of Surgical
Consultants the following comments were
made regarding the use of tourniquets in
World War II:
[Tourniquets]…[u]nless very tightly
applied…are of no service, as they do
not control the bleeding, and if firmly
applied, they act as a general ligature
around the extremity, and can be used
but for a short time without injury to
the limb…. Should a soldier have a
large artery wounded and the hemorrhage be excessive . . . the orderly
should be instructed how to make a
judicious finger pressure. This is
much better than the tourniquet.195
Early in the war, they were used far
too frequently and removed far too often. After a tourniquet had been applied by a corpsman on the battlefield,
it was examined by the first medical
officer who saw the casualty and frequently it was removed by this medical officer. If the tourniquet was not
removed, it was the policy to loosen it
routinely every 30 minutes. In some
cases, death occurred from the cumulative effects of the bleeding which ensued each time the tourniquet was
loosened. The fatalities usually took
place during evacuation by ambulance, on trips lasting several hours,
when the medical corpsman loosened
the tourniquet every 30 minutes as he
had been instructed to do. Many
deaths which could have been avoided
were thus precipitated because no facilities were at hand to control the
hemorrhage which frequently followed
the removal of the tourniquet. Later,
the policy was reversed, and once a
tourniquet had been applied, it was
not loosened or removed, particularly
if the casualty was in shock, until facilities were at hand for the immediate
control of hemorrhage and the replacement of blood loss. It was found
Following World War I, COL Gray noted
the following in his book, Early Treatment
of War Wounds:
When an important artery or vein has
been divided…[and] if…the casualty
clearing station is some distance away
[from a surgical facility]…[a difficult
decision must be faced regarding the
application of] a tourniquet that must
of necessity remain in position for
many hours…. Blind grouping in the
dark in a haphazard attempt to seize
[a bleeding vessel] in the grasp of a
pressure forceps is useless, and generally results in the loss of much additional blood. Unless the operator feels
confident [in his ability to clamp a
bleeding vessel] it is better to rely on
a properly applied tourniquet.3(p.45)
Generally, hemostatic clamps have no role
in the prehospital control of hemorrhage
because it is rare that a hemorrhaging vessel clearly presents itself for clamping. It
38
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
An effective tourniquet should be
placed on an actively bleeding extremity at the earliest possible moment.
to be safe, when a large vessel had
been damaged, to leave the tourniquet
in place for periods of from 4 to 6
hours during cold weather and for
somewhat shorter periods in warm
weather. Rubber tubing proved more
satisfactory than the Army-issue webbing tourniquet.196
At the end of 2 hours, if the patient
was not in shock and if all circumstances were favorable, the medical
officer might cautiously loosen the
tourniquet if facilities were available
for immediate control of hemorrhage.
If bleeding was negligible or did not
recur, the tourniquet might be removed, but the patient was kept under
continuous observations and the tourniquet was left in place for immediate
reapplication.
This last comment regarding the general
ineffectiveness of the Army-issue webbing
tourniquet is interesting because it seems
that despite being recognized as unsatisfactory during World War II, the tourniquet has remained in the inventory to the
present. It is also interesting to note that
during a recent Advanced Trauma Applications for Combat Casualty Care
(ATACC) conference in St. Petersburg
Florida, a panel discussion on tourniquets
concluded that the ½ inch surgical tubing
recommended as a tourniquet during
World War II was the best available field
expedient tourniquet; although concerns
were raised about the high tissue pressures
that could be generated by the use of this
tubing as a tourniquet.197
On no account should a tourniquet on
a patient in shock be removed within 4
to 6 hours of its application unless the
blood volume had been at least partly
replaced by plasma or whole blood.
After this time, the removal or loosening of the tourniquet was a matter of
individual judgment. In many instances, sufficient clotting and spasm
had occurred by this time to prevent
further bleeding.
During World War II, MAJ Luther H.
Wolff, MC, and Capt. Troglier F. Adkins,
MC carried out a study on the use of tourniquets, with a particular focus on patients
in shock. The results of this study formed
the basis of the following regime, which
was in general use when World War II
ended (and which remained standard practice until quite recently):
When a tourniquet was in place, the
temperature of the affected limb was
lowered as much as possible short of
actual freezing.196(p.427-428)
The recommendation, during World War
II, of 4 to 6 hours of tourniquet time, was
empirically derived. Col Gray’s opinion,
based on his experiences from World War
I, was that “…about 80 per cent of limbs
whose blood supply has been cut off by a
tourniquet for a period of three
hours…eventually come to amputation.”3(p.45)
Patients with tourniquets in situ
should have the highest priority for
transportation to the nearest hospital.
The emergency medical tag should indicate that a tourniquet is in place.
Marking the forehead with a red T
was an additional precaution.
A study during the Korean war of 79 major extremity vascular injuries showed that
47% were admitted with a tourniquet in
place for between 40 minutes and 14 ½
39
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
hours; the average time being 4 hours.198
Since the Korean War, a large number of
studies have been done to determine the
optimal maximum tourniquet time before
irreversible tissue damage occurs.199-209
Most of these studies have been done to
evaluate the effect of tourniquet time on
patients undergoing elective orthopedic
surgery and thus patients were relatively
normovolemic at the time of the tourniquet application. To what extent these
studies can be applied to tourniquet use in
combat casualties is unclear.
damage may resolve, nerve damage, if it
occurs, does not.
Forward healthcare providers should be
instructed that, although combat casualties
may experience only minimal discomfort
when the tourniquet is first applied, the
great majority will begin to experience
increasingly severe pain at the tourniquet
site after 30−60 minutes. This pain is described as a dull, burning, aching sensation that becomes increasingly worse until
the tourniquet is removed.212 Patients requiring tourniquet placement should be
given adequate analgesia prior to transport.
In a recent animal study of pneumatic
tourniquet times and the effect of periodic
episodes of reperfusion on muscle injury,
Pedowitz demonstrated that 2 hours was a
time threshold for tourniquet compression
injury. The degree of tissue injury also
depended upon cuff inflation pressure.210
Physiologic and morphologic nerve abnormalities were caused by a 2-hour tourniquet time and necrosis was observed.
With a 4-hour total tourniquet time, skeletal muscle injury beneath the cuff was significantly decreased by hourly, 10-minute
reperfusion intervals.
As previously stated, as long ago as World
War II it was noted that the standard-issue
1.5-inch-wide, cotton-strap tourniquet
(nonpneumatic; NSN 6515-00-383-0565),
was not particularly effective.196(p.427-428) It
is difficult even for a trained healthcare
provider to achieve arterial hemostasis
with this tourniquet, but when applied by
the wounded soldier himself it is essentially impossible to achieve hemostasis,
especially if only one hand is available for
application. During the post-Korean War
conference, “Recent Advances in Medicine and Surgery (19-30 April 1954) at the
Army Medical Service Graduate School
Walter Reed Army Medical Center, Maj.
Mallory made the following comments
about the standard army tourniquet:
Interestingly, this study found that if the
tourniquet time was longer than 2 hours,
episodes of reperfusion tended to exacerbate, not reduce, muscle injury. It is generally taught that muscles are more sensitive than nerves to long tourniquet time
and that tourniquet times > 2 hours and the
use of high pressure (>350 mm Hg in
lower extremities and 250 mm Hg in upper extremities) increases the risk of nerve
damage. It is also generally taught that if >
2 hours is required, the tourniquet should
be deflated for 5 minutes during every 30
minutes of inflation time. Contradicting
this recommendation is a 1999 study by
Mohler et al. that demonstrated that intermittent reperfusion does not reduce neurological injury.211 This study also showed
that although tourniquet-induced muscle
Present methods are time-consuming,
inaccurate as to pressure exerted and
often require excessive manipulation
of the injured part (especially when
applied by a single person). Selfapplication is virtually impossible…the tourniquet to be effective
must be applied before the patient
reaches the aid station. This requires
that it be done in or very near the battle area. This further demands that the
method be very simple and rapid and
40
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
led Special Operations medics to craft
their own tourniquets from triangular bandages and suitable field-expedient windlasses; it also led researchers to try to find
a better tourniquet. Calkins et al. found
that both a ratchet-style and Velcro bladder tourniquet were effective and could be
applied singled-handedly. Despite the potential of the bladder tourniquet to develop
into a “smart tourniquet,” i.e., capable of
periodic self deflation and re-inflation,
Calkins et al. recommended the ratchetstyle tourniquet for field use, primarily
due to its durability, simplicity, ease-ofuse, size, and weight.215
applicable by anyone – characteristics
not possessed by the present
means…We need, critically, a better
tourniquet device (underlying added
for emphasis).213(p.61)
During this same conference it was recommended that, “Not infrequently, a
tourniquet may be used as an emergency
procedure; and, after further evaluation,
bleeding may be controlled by a pressure
dressing.”198 Later during this conference
LTC Hughes stated that, “…a tourniquet
should be applied only tight enough to
control hemorrhage and left in place until
it can be removed by a medical officer
with blood or plasma expander available
to resuscitate the patient. When packs or
pressure dressings will suffice, the tourniquet should be removed and the pressure
dressing applied only tight enough to control the hemorrhage.”198 Interestingly this
recommendation is virtually identical to
that which was recently agreed to for farforward medical care providers.
The revival of interest in the tourniquet in
the mid-to-late 1990’s led to an aggressive
effort to develop, evaluate, and field an
effective tourniquet that could easily be
applied one-handed by a wounded soldier.
The preliminary result of this endeavor
was the selection of a tourniquet that came
to be referred to as the Army One Handed
Tourniquet. Unfortunately, while this
tourniquet could be applied one-handed
(even this tourniquet was not particularly
easy to apply one-handed) it was not particularly effective at occluding arterial
flow in the lower extremities.216
With regard to the current Army-issue
tourniquet, early feedback from Navy
corpsmen in support of the U.S. Marine
Corps during Operation Iraqi Freedom in
Spring 2003 is that once again the 1.5 x
42-inch non-pneumatic tourniquet (NSN
6515-00-383-0565) which was still issued
at that time has proven ineffective.
Corpsmen report that the tourniquet
tended to slip around the thigh or arm
while attempts were made to tighten it,
causing medical personnel to resort to
green slings and sticks to tighten around
pressure points to stem the flow of arterial
bleeding in the extremities.214
Other tourniquets continued to be developed and deployed. The two most widely
deployed being the Combat Application
Tourniquet, or CAT, and the Special Operations Forces Tactical Tourniquet, or
SOFTT. In his 10 May 2005 statement to
the Senate Committee on Appropriations,
Defense Subcommittee, LTG Kiley, Surgeon General, United States Army, noted
that since April 1, 2004 193,897 tourniquets have been issued to deploying
troops; 112,697 of these tourniquets being
either the Combat Application Tourniquet
(CAT) and the SOFTT (Special Operations Forces Tactical Tourniquet). He
went on to say that beginning April 1,
2005 all new soldiers will received spe-
Calkins et al. recently evaluated available
tourniquets and commented that the webstrap tourniquet is inconsistent in stopping
arterial blood flow, even when applied by
someone other than the injured patient
him/herself.215 Recognition of this fact has
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
tourniquets”, which are applied quickly
using materials immediately at hand, to
control potentially lethal hemorrhage
when time and circumstances do not allow
for a detailed assessment and/or when
manpower, or resources are not available.
Such tourniquets are to be removed at the
earliest possible time and the patient reassessed to determine if a tourniquet is actually needed. Second, there are those tourniquets that are “trial tourniquets”; tourniquets that have definitely been determined
to be needed and have been applied in a
careful manner with the intention to leave
in place for up to 2 hours. Finally they
describe “tourniquets of last resort”. These
are the tourniquets that are applied and left
in place after a “trial tourniquet”, which
had already been left in place for two
hours, is removed and bleeding continues
unabated by other hemorrhage control efforts.219
cific instructions on the CAT during Basic
Combat Training.217
Most recently developed and fielded is the
Mechanical Advantage Tourniquet, or
M.A.T., produced by Cybertech. Although
somewhat heavier and more bulky than
some of the previously fielded tourniquets
this author and others feel that this tourniquet is the best of the most recently
fielded tourniquets. This tourniquet is very
easy to use, it can be rapidly applied with
little difficulty using one-hand, and, most
importantly, it is effective at occluding
arterial hemorrhage in both upper and
lower extremities.218 This said, the Combat Application Tourniquet is also quite
effective, and although in this author’s
view somewhat more difficult to use, it is
lighter and less bulky.
Based upon currently available scientific
data, tourniquet times in excess of 2 hours
should be assumed to be associated with
the loss of the distal limb. This may not be
true in every instance; certainly some
limbs will still be salvageable after 2
hours of tourniquet time, especially if the
limb has been kept cold. In fact forward
medical personnel should be advised,
whenever possible, to cool limbs (while
avoiding freezing of the tissue) to which a
tourniquet has been applied in order to
increase the possibility of limb salvage.
There will also be situations where otherwise viable limbs will be lost even when
the tourniquet time has been kept to less
than 2 hours.
The recommendation that is offered here
is that forward healthcare providers should
be given the following instructions:
1. Make every possible effort to
evacuate, in less than 2 hours, all
patients who require placement of a
tourniquet to a facility where surgical control of hemorrhage can be
provided
2. Tourniquet times in excess of 2
hours have a high associated probability of distal limb loss.
3. Although tourniquet placement may
be necessary, it should always be
done with an understanding that no
tourniquet time is considered “safe,”
i.e., there is always a risk of injury
any time a tourniquet is applied.
Navein and Coupland, in their 2003 Journal of Trauma article, noted that a limb
occluded for less than 2 hours is almost
always salvageable while a limb occluded
for more than 6 hours is almost certainly
not salvageable. They conclude that decision making in tourniquet application
should involve viewing tourniquets in one
of three ways. First, those that are “tactical
Research and development should be continued to develop and field an automatic
pneumatic tourniquet that inflates to the
42
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
minimum effective inflation pressure required for hemorrhage control. If clinical
studies confirm the efficacy of periodic
tourniquet deflation, this new tourniquet
should also be able to be set to periodically deflate and re-inflate to allow for
some distal blood flow. The real barriers
to fielding such a tourniquet today is that
such a tourniquet should also be relatively
inexpensive, very durable, and easy to use.
transient. Lieutenant Bering then conceived the idea of using fibrinogen,
converted into fibrin foam, as a matrix…The first applications of fibrin
foam were made in cases in which
bleeding was difficult to control and
the application of muscle was not feasible. The hemostatic effect was evident…It was agreed that the material
was of extraordinary value as a hemostatic agent in neurosurgery.
It…proved of great value in hemophiliacs, in controlling bleeding from
traumatic lacerations, and in maintaining hemostasis during minor surgical procedures such as tooth extractions.”85(p.364)
Other Methods of
Hemorrhage Control
Fibrin Dressing
Early enthusiasm for the use of thrombin
to help control hemorrhage was tempered
by concerns about hepatitis transmission,
and in 1946, all pooled blood products
were withdrawn from military stocks and
the FDA removed the last human fibrinogen from the market in 1977.220 Recently,
new methods have been found to inactivate viruses in pooled plasma and more
extensive purification has enabled production of safe hemostatic agents from pooled
blood products.
Driven by the recognition that the only
place in which combat-related deaths can
really be significantly reduced is in the
prehospital environment, the U.S. Department of Defense medical research
community has increasingly focused on
prehospital care issues; in particular on
hemorrhage control and management of
shock. Recent well-publicized, prolonged,
deaths from hemorrhage of soldiers who
were in the care of medics/corpsmen (e.g.,
during the 1993 operation in Mogadishu,
Somalia and in 2002 at Robert’s Ridge
during Operation Anaconda in Afghanistan) have spurred these efforts. One initiative has been the development and
fielding of the dry fibrin sealant dressing.
Although research in this area has recently
been re-energized and now focused on the
far-forward use of fibrin, the use of fibrin
for hemorrhage control had begun to be
explored as early as World War II.
Increased focus on improving prehospital
hemorrhage control was the catalyst for
development of dry fibrin sealant dressing
(DFSD) by COL John Holcomb, MD. The
DFSD is designed for direct application to
bleeding surfaces for control of serious
hemorrhage 221-225. The dry thrombin and
fibrinogen used on the dressing provide, in
great excess, the last two clotting factors
in the coagulation cascade so when blood
from a hemorrhaging vessel comes in contact with the dressing, a strong, clot-like
adhesive is quickly formed.220 The fibrin
dressing has been shown to effectively
control both external221 and internal hemorrhage223, 224, 226-230 in animal models.
When thrombin first became available, Lt. Edgar A. Bering, Jr., Mc,
USN and Dr. Bailey had applied it in
solution to bleeding points in several
cranial and spinal operations. It did
no harm…but its effect was entirely
43
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Clifford C. Cloonan, MD
Circulation
Freedom, but it was not used in any instance.
In an unblinded, randomized, prospective
trial using a caprine ballistic wounding
model, the DFSD reduced both total blood
loss and blood loss per kilogram of body
weight as compared to a standard gauze
dressing. By 20 minutes post-injury, the
mean blood pressure in the DFSD-treated
group had returned to its pre-injury level
while at the same point in time, the mean
blood pressure of the gauze-dressingtreated group remained near its post-injury
low.225 All dressings in the study were
applied in the same manner as conventional gauze dressings.
In any case, given their higher level of
medical training, the field performance of
this dressing when used by Special Operations Combat Medics and Special Forces
medics may not be equivalent to that
which may later be observed in conventional medics/corpsmen.
It is hoped that someday this dressing and
other hemostatic agents will help to increase the number of survivors of combat
wounding. Unfortunately the cost of the
DFSD is quite high (currently $1,000 per
dressing) and the price is not expected to
fall below $300 per dressing155 even when
it goes into full-scale production. This
high cost will likely restrict the widespread usage of this dressing and thus,
even if it is highly effective, it is unlikely
to have a significant impact on survival
because it won’t be widely available at or
near the point of wounding.
There is some evidence to suggest that the
DFSD is more sensitive to precise application for optimal function than is the standard gauze battle dressing. In a preliminary study of the efficacy of the DFSD in
a simulated land-mine injury in a caprine
model done by LTC Paul Dougherty at the
Joint Special Operations Medical Training
Center at Fort Bragg in 1999, it appeared
that the DFSD did not perform as well as a
conventional dressing unless the dressing
was tucked down into the depth of the
wound to ensure that the fibrin was in
close proximity to the point of bleeding.
Although this study may not have been
completed and no other discussion of optimal position of the DFSD appears in the
literature, COL Holcomb, developer and
strong proponent of the DFSD, admitted
that, “These agents [hemostatic dressings]
are not magic; they must be placed in apposition to the major bleeding source.”155
QuikClotTM
In 2002, a study was conducted at USUHS
to evaluate the efficacy of several different, commercially available hemostatic
agents in reducing blood loss after lethal
uncontrolled hemorrhage in Yorkshire
swine.231 A complex groin injury that included complete division of the femoral
artery and vein was inflicted, and after 5
minutes the animals were randomized to
the following groups: (1) no dressing, (2)
standard dressing, (3) standard dressing
plus aggressive resuscitation, (4) standard
dressing plus Rapid Deployment HemostatTM (RDH, Marine Polymer Technologies], (5) standard dressing plus QuikClotTM hemostatic agent (Z-Medica), (6)
standard dressing plus TraumaDEXTM
(Medafor, Inc.).
During recent military operations in Iraq
(Operation Iraqi Freedom) the DFSD was
fielded under a special investigative protocol approved by the FDA that ceased
following conclusion of major combat
operations. During this approved protocol,
the DFSD was fielded to Special Operations combat medics involved in ongoing
combat operations in Operation Iraqi
44
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
In this Alam study all groups received one
liter intravenous saline except Group 3,
which received unlimited saline, with the
goal of maintaining a systolic blood pressure >100 mm Hg. There were six animals
in each group. Application of a wound
dressing decreased mortality in all groups
as compared to the no dressing group
(Group 1), which had 83% mortality. Because of the small size of the groups, this
difference was only significant for the
QuikClotTM hemostatic agent, which had
0% mortality. Application of the standard
dressing alone decreased mortality to
33.4%.
exothermic reaction reached as high as
65°C (149°F). Fortunately, in vivo, the
maximum recorded temperature in tissue
did not exceed 45°C (113°F). As noted by
Dr. Alam, this was probably because the
large volume of blood and the surrounding
tissue acted as a heat sink and the distribution of QuikClotTM over a wider area
minimized the amount of heat at any specific point.232
An interdisciplinary, multiservice panel of
medical personnel chaired by COL Dave
Burris was convened at USUHS in February 2003 to review Dr. Alam’s findings
and to make a recommendation to the U.S.
Marine Corps regarding the advisability of
fielding QuikClotTM to corpsmen. QuikClotTM was recommended for fielding
with certain provisions. This panel concluded the following:
RDHTM is a poly-N-acetylglucosamine
derived from algae that is backed by 4”x
4” gauze. QuikClotTM is a granular zeolite
that adsorbs water (creating significant
heat of adsorption) and promotes clot formation when it is poured onto a bleeding
site. TraumaDEXTM is a powder-like agent
that consists of bioinert microporous particles that absorb water and promote clotting by producing a gelling action.
• QuikClotTM causes a variable amount
of local tissue damage when used in
animal models. Damage varies from
none to as much as 5 mm into surrounding tissues. Localized burn injury to regional blood vessel walls and
nerves could lead to morbidity if the
casualty survives.
In May 2002, the FDA approved QuikClotTM for clinical use. Based, in part,
upon the findings in this study the United
States Marine Corps decided to consider
fielding QuikClotTM to medical personnel
preparing to engage in impending combat
operations in Iraq. Because of some concern about the potential for injury that
might occur as the result of the exothermic
heat of adsorption that is created when
water (or blood) is added to QuikClotTM, a
study was done by Dr. Hasan B. Alam at
USUHS to assess the degree of burn injury that might be produced during clinical
use of this product.
• In one animal study, wounds closed
primarily after the use of this agent
became infected. Because combat
wounds should not be closed primarily, the significance of this finding is
unclear.
In vitro, depending upon the amount of
blood/saline and depending on the rate of
addition, the temperature varied considerably. In the lab, with just the right mixture of blood, saline, and QuikClotTM the
• QuikClotTM controls hemorrhage. The
risk of tissue damage is offset by the
potential to save life in otherwise uncontrollable external hemorrhage.
• Given the risks of tissue damage,
QuikClotTM should not be used when
there is no life-threatening hemorrhage.
45
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
• QuikClotTM should only be used to
treat external wounds.
cording to LT Webb, “QuikClotTM
was everywhere but the wound.”
• Iraqi civilian, female, shot in femoral
artery. She suffered severe arterial
bleeding. Patient bled out. QuikClotTM unable to be applied effectively due to pressure of blood flow
from wound. Patient died.
• QuikClotTM should only be used after
properly applied standard methods of
hemorrhage control have failed.
• QuikClotTM should be an accountable
item that requires reporting each time
a packet is utilized.233
• An LAR Marine was shot in the femoral artery. QuikClotTM was applied
to the heavily bleeding wound. The
pressure from the blood soon caused
the QuikClotTM to be pushed out of
the wound and rendered ineffective. A
tourniquet was applied instead. The
patient died.
Based upon the demonstrated efficacy of
QuikClotTM and upon the panel’s recommendation, QuikClotTM was fielded for
use to U.S. Navy corpsmen supporting the
U.S. Marine Corps during combat operations in Iraq.
The following comments regarding QuikClotTM were included in an early U.S. Marine Corps Operation Iraqi Freedom After
Action Report on the performance of various items of equipment including QuikClotTM. 234 These comments do not reflect
a comprehensive assessment of the effectiveness of QuikClotTM in treating casualties, but they are worth consideration.
It was noted that QuikClotTM may work if
applied in a “buddy system” manner, with
one individual applying the QuikClotTM
substance while another quickly applies
sterile gauze to the wound. However, applying the QuikClotTM as directed appeared to be ineffective. Direct pressure
and tourniquets were used instead. It was
noted in the report that the Marine Expeditionary Unit medical officer who was interviewed had a more favorable opinion of
the efficacy of QuikClotTM and the author
of the report recommended that further
study of this item be done (unfortunately
data regarding the use of this item were
not collected in a rigorous fashion and
thus it will not be possible, even in a retrospective way, to truly assess the efficacy
of QuikClotTM when used to treat combat
casualties during Operation Iraqi Freedom).
2D Tank Battalion Surgeon LT Bruce
Webb (USN) stated that QuikClotTM was
ineffective (specifically, it was ineffective
on arterial bleeding). Battalion corpsmen
attempted to use QuikClotTM in three separate occasions:
• Wounded Iraqi civilian. Shot near
brachial artery. QuikClotTM was applied per the instructions. The substance dried but was flaking off.
Standard direct pressure applied by
corpsman proved more effective on
the patient.
HemConTM
• Iraqi civilian shot in back with punctured spine. QuikClotTM applied to
severe bleeding. Pressure from bleeding sprayed QuikClotTM away. Ac-
After Dr. Alam’s initial study of available
hemostatic dressings the FDA approved
another hemostatic agent, the HemConTM
hemostatic dressing. HemConTM is a chitosan-based, poly-N-acetyl-d-glucosamine
46
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
quate training of the user will be a key
factor in obtaining the desired benefit.”
This is most certainly true. They go on to
point out that, “For the first time since the
Crimean War, the KIA rate has markedly
dropped below the historic 20%” with
there being an overall KIA rate during
Operation Iraqi Freedom of only 12.2%
(citing a Washington Post article by Loeb
dated 28 December 2003) – implying that
the use of hemostatic dressings contributed to this decline.
-- a naturally occurring substance. This
hemostatic dressing is described by Alam
et al232 and is discussed in a review of hemostatic dressings for first responders by
Neuffer et al.235
Pusateri et al. conducted a study of the
efficacy of this product in controlling severe hemorrhage from a hepatic injury in a
swine model.236 They compared the chitosan dressing to gauze sponges in terms of
ability to reduce hemorrhage and improve
survival. Following induction of a large
liver injury, the animals were resuscitated
with Ringers lactate back to their baseline
MAP at a rate of 260 mL/min (note that
this is very aggressive fluid resuscitation).
The dressings were applied directly to the
areas of bleeding and compression was
applied. The amount of post-treatment
blood loss was determined by suctioning
of the shed blood from the abdominal cavity.
While the assertion in the Alam article
that the KIA rate has declined dramatically during Operation Iraqi Freedom may
be true there is good reason to suspect that
it is not; at least not to anywhere near the
extent stated. First, at the time of their article’s publication the conflict was still ongoing so the final numbers, whatever they
are, have not been tabulated and analyzed.
Second, this author is unaware of any systematic, comprehensive, study of battle
and disease-non-battle injuries and deaths
that has been conducted during this war at
the time of this writing (an article in the
Washington Post is anecdotal at best). Finally, and perhaps most importantly, any
decline in the KIA rate, if one actually
exists, is far more likely the result of the
widespread use of soft and hard body armor in this conflict. None of this is to suggest that there is no value in the procurement and distribution of hemostatic agents
to pre-hospital combat health care providers. It is rather intended to make clear that
there is no substitute for training and for
the proper application of basic first-aid
procedures for hemorrhage control and to
underscore that injury prevention or attenuation is far more important than the
availability and use of these new hemostatic agents.
Post-treatment blood loss was significantly reduced in the chitosan dressing
group as compared to the gauze sponge
group (p<0.01) and survival was also significantly better in the chitosan dressing
group (7/8 compared to 2/7). Whether this
dressing would be more effective than a
properly applied standard battle dressing
at controlling hemorrhage in an extremity
injury in a combat casualty is unknown,
however. Given that current resuscitation
protocols call for limited to no volume
resuscitation until hemostasis is achieved,
it is unclear how this dressing would have
compared to gauze if no effort had been
made to raise the MAP back to pre-injury
levels.
It is worth noting that Alam et. al.,232 in
their review of the various hemostatic
agents considered for use by the U.S. military, concluded that, “Clearly hemostatic
agents are not a substitute for, but an adjunct to, the standard treatment, and ade-
Factor VII Injection
47
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
injury initiates the coagulation cascade,
and in extensive injury this may trigger a
disseminated intravascular coagulation
(DIC)-like picture that consumes clotting
factors and leads to sustained bleeding.
Traditionally, this has been a contraindication to the use of rFVIIa. Despite these
concerns, clinical experience with rFVIIa
has been relatively free of serious adverse
events in general and specifically there has
been a low risk of serious thromboembolic
complications.241
Future methods of hemorrhage control
may include the use of recombinant Factor
VII and/or other procoagulants. Factor VII
has long been available for use in hospital
settings to treat bleeding patients with inherited or acquired coagulation factor deficiencies. The major problem that has
significantly limited the use of Factor VII
for hemorrhage control, even for this
group of patients, has been the risk of disease transmission. Historically, Factor VII
was derived from pooled blood products
and was associated with a high risk of
hepatitis, and more recently, HIV, transmission. Recombinant Factor VIIa
(rFVIIa), which is now available, does not
have these risks. It is indicated for the
treatment of hemorrhage in patients with a
genetic Factor VII or Factor IX deficiency
(hemophilia A and B) with significant
bleeding; albeit at great expense. In the
United Kingdom, approximate costs of
rFVIIa (converted to U.S. dollars from
2002 U.K. pounds) were $1,130 for 1.2
mg; $2,260 for 2.4 mg, and $4,520 for 4.8
mg). For treatment of severe hemorrhage
in an adult, the cost of one dose exceeds
$5,600.237
Today, rFVIIa is not even approved for
use in U.S. hospitals to treat general
trauma patients, nor is it approved for use
in the prehospital setting. There is, however, some reason to believe that such
treatment might someday be considered at
or near the point of wounding. Given the
young age and pre-existing good health of
the great majority of combat casualties, it
may be that rFVIIa, or a related procoagulant, could someday be safely given in the
field by prehospital personnel.
Other Methods of Hemorrhage
Animal studies have demonstrated the efficacy of rFVIIa in reducing mortality in
lethal uncontrolled hemorrhage models.238,
239
Recombinant Factor VIIa has recently
been successfully used off-label to treat
patients with exsanguinating, and otherwise uncontrollable, hemorrhage due to
trauma.240-242 Occasionally, the results
have been quite remarkable despite the
fact that, because the rFVIIa was given as
a last resort, a number of the patients ultimately died, often from causes other than
continued hemorrhage.
Control
Stabilization of fractures, especially pelvic
fractures, is very effective at reducing or
even stopping, continued bleeding. Major
pelvic fracture can be associated with uncontrolled hemorrhage and mortality as
high as 50%. Venous bleeding, which accounts for as much as 90% of pelvic hemorrhage, responds favorably to pelvic bone
stabilization.243
New external pelvic stabilizers are now
available that can be applied at the bedside, but such devices will almost certainly never have a role in the stabilization
of pelvic fractures outside of a medical
treatment facility. Stabilization of pelvic
fractures can, however, be achieved with
Not surprisingly, the major concern with
administration of rFVIIa to patients without a known deficiency is the risk of
thrombotic complications. Exposure of
subendothelial tissue factor at the site of
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
devices that prehospital personnel either
already carry, such as the PASG 181, 184, 244
or bed sheet 245, or could carry (e.g., Geneva pelvic belt, London pelvic splint,
Trauma Pelvic Orthopedic Device (TPOD), etc…).
mize the occasionally significant blood
loss often associated with these injuries.
Finally, stabilization of large, soft-tissue
injuries of the thigh and buttocks through
bandaging and splinting can help control
bleeding even when there is no associated
fracture.
Stabilization of long-bone fractures, particularly femur fractures, can also mini-
Other Types of Shock
As noted above, hemorrhagic shock is the
primary circulatory problem of concern in
the management of the combat casualty at
or near the point of wounding. Other
forms of shock occur in combat casualties,
although they are much less common. Although disease and non-battle injury continue to be significant causes of morbidity
and lost man-days in the combat zone,
they are an uncommon cause of death and
are outside the scope of this discussion.
Therefore, the other forms of shock, i.e.,
hypovolemic shock from other than hemorrhage, neurogenic, cardiogenic, anaphylactic, and septic shock will only be discussed here in the context of those shock
states found in combat.
suffered burn injuries, reflecting the high
incidence of burn injury associated with
naval warfare.248
Increased use of petroleum-powered vehicles on the modern battlefield has contributed to an increase in the number of burn
injuries in land combat from both combat
and non-combat causes. Although not
used against U.S. forces in recent conflicts, fuel-air explosives and enhanced
blast weapons are increasingly being used
and will likely contribute to an increase in
burn injuries in the future.
In armored warfare, a combined injury of
burn, primary blast, and penetrating injury
is called the “Anti-Tank Missile Syndrome.” The management of combined
injury is problematic because each individual mechanism may ideally require
different fluid resuscitation strategies (see
earlier discussion on this issue above).
Hypovolemic Shock – NonHemorrhagic
Burns
As noted elsewhere in this series 246, combat-related burns have historically accounted for about 3% of all combat injuries. When considering modern warfare
since World War II, particularly armored/mechanized warfare, this percentage has been as high as 10.5% (1973 Yom
Kippur War) 247. During the conflict in the
Falklands 14% of all UK casualties were
burned and 34% of Royal Navy casualties
Burns cause hypovolemia and shock
through a variety of means. In burns, the
intravascular and interstitial spaces are
depleted as fluid exudes from the skin and
vasoactive inflammatory mediators cause
intravascular fluid to leak into surrounding
tissues. All of this can happen soon after
burn injury. When burns cover approximately 20% total body surface area
(TBSA), hypovolemic shock may occur.
49
Immediate Care of the Wounded
Clifford C. Cloonan, MD
Circulation
of 5% dextrose in water (D5W) during the first 24 hours post burn.
Delays in resuscitation of burn victims can
be costly. It has been shown that the time
to intravenous access and initiation of
fluid resuscitation is a major predictor of
mortality in pediatric patients with greater
than 80% TBSA burns.249 In one study, it
was demonstrated that if intravenous access was not established within 2 hours
from the time of injury, there was a significant increase in mortality.250 The recommendation of this study was that if initial attempts at vascular access were unsuccessful, intraosseous access should be
obtained and fluid administered.
• Consensus Formula Promulgated by
the Advanced Burn Life Support
Course, the Consensus fluid formula
recommends 2-4 mL Ringers lactate/kg/TBSA burn for the first few
hours post-burn, with half of the calculated volume given in the first 8
hours and half over the remaining 16
hours.252
Hypertonic saline, both alone and combined with a colloid (Dextran), has also
been recommended for the treatment of
burn victims (see above), but because
7.5% NaCl/6% Dextran-70 is not currently
FDA-approved, it will not be discussed
further here.253 In general, crystalloid resuscitation with isotonic Ringers lactate is
considered the best option in the acute
phase.
Many different fluid resuscitation formulas for burn resuscitation have been described. These differ in the amount of
crystalloid and colloid to be given, and in
the tonicity of the fluid. A recent review
article by Nguyen et al. notes that colloid
administration with albumin or plasma
protein substitutes helps maintain oncotic
pressure after acute resuscitation but in
randomized trials has not been shown to
improve clinical outcomes.251 According
to these authors, the consensus is that the
administration of colloid is unnecessary
for patients with less than 40% TBSA
burns and during the first 8 hours for patients with larger burns. No single fluid
resuscitation protocol has proven superior
at reducing the severe systemic edema that
accompanies fluid resuscitation of severe
burn injury; a partial list includes the following:
When, for whatever reason, intravenous or
intraosseous infusion of fluids is not possible, oral rehydration of moderately
burned patients with the World Health
Organization Oral Rehydration Solution is
an option worth considering; certainly one
that should receive further study. In an
Egyptian study by El-Sonbaty, an oral rehydration solution called Rehydran-n
(CID Co. Giza, Egypt) was used to treat
children with 10−20% TBSA burns.254
Rehydran-n is formulated as a 5.5-gram
packet, which, when dissolved in 200 mL
water, gives a concentration of 90 mEq
sodium, 20 mEq potassium, 30 mEq bicarbonate, 80 mEq chloride and 111 mEq
glucose per liter.
• Parkland Formula The most commonly used formula in adults, the
Parkland formula employs crystalloid
resuscitation with 4 mL/kg/%TBSA
burn, using Ringers lactate in the first
24 hours post-burn.
All of the children in the study did well,
despite developing low serum sodium levels. Because these low sodium levels were
almost certainly due to the low sodium
content of the Rehydran-n solution, ElSonbaty recommended that the 5.5-gram
• Brooke Formula The Brooke formula
recommends 2 mL Ringers lactate/kg/% TBSA burn plus 2000 mL
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Clifford C. Cloonan, MD
Circulation
penetrating or blunt injury, inhalation burn
injury, or other causes of hemodynamic
instability should be sought. Resuscitation
should begin as soon as possible after the
time of burn injury. Unfortunately, especially in the combat environment, delays
in adequate resuscitation are, and will remain, common and this may lead to unnecessary loss of life.249
packet be constituted with 150 mL instead
of 200 mL water to increase the sodium
content to120 mEq/L. The author concluded that the advantages of this approach include (1) simplicity of use (2)
low cost (3) possibility of use as a first-aid
treatment until patient arrives at a hospital
(4) no risk of fluid overload, and (5)
avoidance of all the difficulties and complications of intravenous infusions. Oral
rehydration with a suitable solution, therefore, may reasonably be recommended for
moderately burned combat casualties who
can tolerate oral fluids and in whom intravenous access cannot be obtained. More
severely burned patients will have a burninduced ileus and will not be able to tolerate oral fluids.
Cardiogenic Shock
Cardiogenic shock results when cardiac
action cannot deliver a circulating blood
volume adequate for tissue perfusion. The
most common cause of this in the general
population is myocardial ischemia or infarction. In the combat setting, cardiogenic shock in a young soldier is more
likely caused by cardiac tamponade or
cardiac contusion from blunt chest trauma.
Intravascular volume status of burn patients must be re-evaluated on a frequent
basis during the acute phase. Monitoring
urine output closely is the best indicator of
adequate resuscitation. Unfortunately, this
can’t be done easily or accurately in the
prehospital environment. Urine output in
children should be maintained at 1
mL/kg/h, whereas for adults, 0.5 mL/kg/h
is sufficient. Although early and substantial fluid resuscitation is indicated for patients with significant burns, it is essential
to avoid over-aggressive resuscitation,
which can lead to pulmonary edema. This
is especially important in casualties with
inhalation burn injuries, who are at increased risk of pulmonary edema due to
increased pulmonary vascular permeability.
Pericardial tamponade as a cause of combat-associated death was recognized and
well described during the Civil War. The
Confederate Surgeon General even noted
that some combatants with this injury
might survive stating that,
When the heart is injured [and yet the
man lives a short period]…the pericardium soon becomes filled with
blood; the action of the heart is mechanically impeded, and, sooner or
later, depending upon the size of the
wound and the facility for letting out
blood, it ceases its pulsation. Reports
of cases are not very rare in which
small, oblique incised wounds of the
heart have been recovered from…”
None of the recommended burn protocols
should be considered a substitute for constant reassessment of urine output and
volume status within the context of the
patient’s overall clinical picture. An increased fluid requirement in a burned
combat casualty should raise the index of
suspicion for concomitant injury. If there
is an increased fluid requirement occult
255(p.281)
The true incidence of both cardiac tamponade and cardiac contusion in modern
combat casualties is unknown. There are
certainly case reports of pericardial tam-
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Clifford C. Cloonan, MD
Circulation
emergency department, much less a combat environment, seems unlikely. The
presence of pulsus paradoxus (>10 mm
Hg decrease in systolic blood pressure
during inspiration), which is sometimes
found in pericardial tamponade, could
help make this diagnosis. Unfortunately,
given the training of the average combat
medic, the available equipment, and the
chaos of the combat environment, it is not
likely that pulsus paradoxus could be used
to reliably diagnose pericardial tamponade
in the field.
ponade found at autopsy. During World
War II, the 2nd Auxiliary Surgical Group
recorded that only 3.3% (75 of 2267) of
those with thoracic wounds had cardiac or
pericardial involvement, and in those
cases where there was pericardial involvement tamponade was not present in
all cases. Given that thoracic injuries only
constitute 7% of all combat injuries256
(probably less than this in current operations due to widespread use of body armor) and assuming that all of these 75
WWII casualties had pericardial tamponade this means that at most only .231%
of all combat casualties in World War II
had pericardial tamponade.257
The definitive treatment of pericardial
tamponade involves thoracotomy, with
opening of the pericardium and repair of
the underlying injury. Pericardiocentesis,
which is advocated by current ATLS
guidelines, is a temporizing, not definitive,
measure. The technique, as described in
the ATLS manual, requires monitoring of
the patient’s ECG “…before, during, and
after the procedure.” Evidence of a “current of injury” on the ECG (extreme ST-T
wave changes or widened and enlarged
QRS complex) indicates that the pericardial needle should be withdrawn. 49 This
cannot be done at or near the point of
wounding.
It is noted in the above cited WWII report
that, “In comparison to the frequency with
which it is noted in civilian cardiac
wounds, tamponade has been an infrequent finding.” The absence of tamponade
was attributed to the large wounding missiles used in combat, which create a hole
in the pericardium so large that tamponade
does not occur 257. Whether this would be
the case today, with an increased use of
improved conventional munitions, is unknown. In this historical account of a busy
combat surgical unit, it is worth noting
that in more than 50% of the cases in
which cardiac injury was ultimately diagnosed, the cardiac wound was undiagnosed prior to surgery.
Although pericardiocentesis, without early
thoracotomy, can certainly be performed
at or near the point of wounding, the question is, “Should it be recommended?” The
ATLS pericardiocentesis recommendation
assumes that a surgeon, with the ability to
perform the appropriate definitive procedure, is either immediately available or
can be quickly reached. This is rarely the
case when combat casualties are cared for
at or near the point of wounding.
When both pericardial tamponade and
hemorrhagic shock are present, it is very
difficult to make the proper diagnosis,
even in a hospital setting. The classic triad
associated with pericardial tamponade: (1)
hypotension, (2) muffled heart sounds,
and (3) distended neck veins (Beck’s
triad) are either not present (distended
neck veins) or are readily attributable to
hemorrhagic shock (hypotension); and
finally what exactly constitutes muffled
heart sounds is unclear and, in any case,
accurate diagnosis of this finding in a busy
Special Operations Medics are taught to
perform pericardiocentesis whenever either Beck’s triad [hypotension, distended
neck veins, muffled heart sounds] is present or when hypotension alone is coupled
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Clifford C. Cloonan, MD
Circulation
would not benefit from the procedure (assuming that any would benefit) would be
exposed to the risks of iatrogenic injury
(pneumothorax, inducing pericardial tamponade, and inducing potentially fatal cardiac arrhythmias).
with a wound likely to cause pericardial
tamponade in a patient in whom other resuscitative efforts have been unsuccessful.
Unfortunately, in a combat setting, most
patients who have tamponade are likely to
be hypovolemic from other penetrating
wounds so distended neck veins are
unlikely, and, as noted above, hearing
“muffled heart sounds” in a combat setting
is problematic.
If there were evidence that performing
pericardiocentesis at or near the point of
wounding would benefit patients with
pericardial tamponade, it might still be
reasonable to recommend the procedure,
inherent risks notwithstanding; unfortunately there is not.
Is pericardiocentesis in a combat setting a
reasonable recommendation for Special
Operations medics who are trained to, or
above, the paramedic level? Is it a reasonable recommendation for the average
combat medic? Is it a reasonable recommendation for any level of provider at or
near the point of wounding? These are
difficult questions. Reasonable answers
require an assessment of the likelihood of
benefit (based upon the incidence of the
condition in the population and the efficacy of the procedure) as compared to the
likelihood of “cost” (risk of iatrogenic
injury if done correctly or incorrectly and
if indicated or not indicated).
When Dr. Ken Mattox, a contemporary
leading trauma surgeon, was asked
whether he would recommend the performance of pericardiocentesis by combat
medics at or near the point of wounding,
he said that he would not. Absent almost
immediate surgical correction of the underlying condition, Dr. Mattox did not feel
that pericardiocentesis would improve
survival (personal conversation with author circa 1999).
Without clear benefit, only the risks remain, so until clear evidence of benefit is
found, pericardiocentesis should not be
performed at, or near the point of wounding. A small bolus of fluid, however, may
help improve cardiac output in a patient
with cardiac tamponade because increasing the preload will help overcome the
resistance to distention of the left ventricle.
Pericardial tamponade appears to be a
very uncommon condition in combat
casualties; the exact incidence is unknown. It seems likely that when it occurs,
it would be rare to find all elements of
Beck’s triad present. It is probable that in
combat casualties, pericardial tamponade
would usually be combined with some
degree of hemorrhagic shock and/or preexisting hypovolemia from dehydration.
The incidence of hemorrhage shock, as a
cause of fluid-unresponsive hypotension,
is certainly much higher than the incidence of pericardial tamponade.
Blunt trauma to the chest can cause dysrhythmias and/or can produce a cardiac
contusion with resultant impaired cardiac
function, both of which can lead to reduced cardiac output and, in some cases,
cardiogenic shock. These rarely occur on
the battlefield, which is fortunate because
it is generally not possible for combat
medics to diagnose or treat casualties with
these conditions. In the proper settings,
All of this raises the likelihood that, if the
above guidelines are followed, that pericardiocentesis will be performed many
times more often than required. Thus a
potentially large number of patients who
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Clifford C. Cloonan, MD
Circulation
occur from blunt than from penetrating
injury.258
prehospital personnel should consider cardiogenic shock in the differential of a
combat casualty with hypotension.
Traumatic spinal cord injury is associated
with significant alterations in blood pressure, pulse rate, and cardiac rhythm. The
immediate, acute response, to spinal cord
injury is a systemic pressor response with
a widened pulse pressure. This occurs
within a few seconds of injury and persists
for several minutes. Activation of the
sympathetic nervous system and adrenal
medulla is responsible for this initial, transient, pressor response.262 This hypertensive response is often followed by a prolonged hypotensive phase (neurogenic
shock) caused by an interruption of neuronal sympathetic activity.
Neurogenic Shock (Spinal Cord
Shock)
In the civilian setting, the great majority of
spinal column injuries are caused by blunt
trauma, with about 45% being caused by
motor vehicle crashes, 20% by falls, and
15% by sporting accidents. Only 15% are
due to penetrating trauma.258 In the Soviet
combat experience in World War II, over
99% of all spine injuries were caused by
penetrating wounds – a significant difference.259 The exact incidence of spine injury in combat casualties is difficult to
ascertain as a significant number of casualties with such an injury die at, or near,
the point of wounding. In World War II
only 1.5% of casualties arriving alive at a
general hospital had spinal cord injuries.260
More recently, during the Vietnam War, it
was found that approximately 13% of all
combat casualties have, among their injuries, a penetrating neck wound261 – but
only a relatively small percentage of these
have an injury to the spine, and even a
smaller number have an injury to the cord.
Due to the increased use of body armor
and the associated relative decrease in the
numbers of penetrating combat injuries,
the relative percentage of combatassociated blunt trauma spinal cord injuries from falls and vehicle and aircraft
crashes is likely to rise in more modern
conflicts.
Because the sympathetic nerves exit from
above L-1, any patient with a spinal cord
injury above that level could potentially
have some degree of neurogenic shock.
The sympathetic cardiac nerves exit the
spinal cord between C-1 and T-5, so cord
injury at or above T-5 may be associated
with significant bradycardia that may further worsen any hypotension. Bradycardia
may also be caused by a trauma-induced
reflex parasympathetic discharge. Cardiovascular instability can persist for days to
weeks.263
Sympathetic tone is most important to
maintaining the blood pressure in the erect
position so in the wounded supine/prone
casualty, the loss of sympathetic tone has
a less of an effect on tissue perfusion than
might be anticipated. Most studies of neurogenic shock define hypotension as being
present when systolic blood pressure is <
100 mm Hg, yet systolic blood pressure >
90 mm Hg is certainly adequate for tissue
perfusion; the currently recommended
threshold for volume-resuscitation of patients with uncontrolled hemorrhagic
shock is systolic blood pressure < 85 mm
Hg.
Neurogenic shock, in which the normal
vasomotor tone derived from sympathetic
afferent nerves is lost and blood pressure
drops, can occur in both partial and complete spinal cord injury from both blunt
and penetrating causes. Some data suggest
that neurogenic shock is more likely to
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Clifford C. Cloonan, MD
Circulation
warm, pink, dry skin instead of cold, cyanotic, moist skin. Other clues to a diagnosis of neurogenic shock, aside from hypotension with warm dry skin, are varying
degrees of paralysis, and, if the spinal lesion is above C-5, some degree of respiratory difficulty that varies from abdominal
(diaphragmatic) breathing to apnea.
In a study by Zipnick et al of patients with
penetrating spinal cord injuries primarily
from gunshot wounds, only 5 of 75 patients (6.6%) with penetrating spinal cord
injury had clear-cut, isolated, hypotension
that could be attributed to neurogenic
shock. Although most patients (78%) had
complete spinal cord injury, only 18
(24%) were hypotensive in the field; an
additional 5 patients developed hypotension after reaching the emergency department (hypotension was defined in this
study as systolic blood pressure < 100 mm
Hg) for a total of 23.258 Of these, 18 had
significant blood loss to explain their hypotension. Patients with cervical and upper thoracic injuries had significantly
lower heart rates in the emergency department than did those with lower cord
injury, but the lowest mean heart rate was
71 beats per minute.
From the perspective of the healthcare
provider resuscitating the combat casualty
at or near the point of wounding, the question is, “Does it matter, in terms of fluid
resuscitation, if the casualty has a spinal
cord injury and may have neurogenic
shock?” The answer is, “Probably not.”
First, it should be assumed that all combat
casualties, irrespective of mechanism,
have ongoing hemorrhage. Zipnick et al.
conclude their study with the comment
that, “Patients with early hypotension following penetrating spinal injury should be
assumed to have a major blood loss injury...hypotension should not be ascribed
to spinal cord injury until an exhaustive
search for blood loss is completed and is
clearly negative”.258 This comment is applicable to victims of blunt trauma as well.
Second, the current combat medic resuscitation protocol fluid resuscitation is dictated by mental status changes, the presence or absence of a radial pulse, and response to a fluid challenge. This protocol
is reasonable for the casualty with neurogenic shock as well because the most important objective, in the short term, is to
maintain adequate cerebral perfusion. Because the initial assumption should be that
hypotension in a combat casualty with a
possible cord injury is the result of hemorrhage, if fluid resuscitation is indicated,
the type of fluid used should be the same
as that recommended for hemorrhagic
shock.
Patients with cervical and upper thoracic
spine injuries did not have a greater risk of
initial hypotension; in fact, patients with
lumbar cord injuries were most likely to
be hypotensive, presumably because of a
higher amount of blood loss. The authors
noted that, “Whereas patients with blunt
spinal cord injuries are at risk for concomitant blood loss injuries, 70% of those
with hypotension have neurogenic shock.
This is far different in patients with penetrating spinal cord shock injuries in whom
pure neurogenic shock is relatively
rare.”258
Casualties in neurogenic shock, while suffering from the same basic underlying pathology of inadequate tissue perfusion that
is present in all the other forms of shock,
are different from those with some degree
of hypovolemia in that there is no vasoconstriction (indeed this is the underlying
problem). Replacement of vasoconstriction with vasodilation means that clinically, patients in neurogenic shock have
Given the underlying pathophysiology in
neurogenic shock, it would seem reasonable to suggest using the PASG, if one is
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Clifford C. Cloonan, MD
Circulation
available, because the PASG mechanically
increases afterload. The problem is, as has
been pointed out, that even when neurogenic shock is present, there is often concomitant hemorrhagic shock, often with
uncontrolled blood loss, and the PASG is
contraindicated in such a circumstance.
days after wounding and so would rarely
be a cause of shock that would be treated
at, or near, the point of wounding. In the
case of penetrating abdominal wounds
septic shock may, however, occur in less
than 24 hours in some instances. In a
study by Klein et al. 264 there were eightyeight episodes of wound associated infection identified among 624 consecutively
admitted battlefield casualties. Ninety-one
per cent of infections occurred despite
administration of a prophylactic antibiotic
and in 65% of cases multiple antibiotics
were being administered; so early antibiotic administration does not eliminate the
risk of septic shock. In fact the practice of
antibiotic wound prophylaxis may, overall, have a negative effect on battlefield
wound infections by doing little-tonothing to prevent them and by increasing
the risk of infection with a resistant organism.
Furthermore the literature fails to demonstrate the efficacy of PASG to treat neurogenic shock. There is one situation in
which it would still seem reasonable to
recommend PASG in the management of a
patient with presumed neurogenic shock,
and that is in any circumstance in which
such a patient would be lifted in a head-up
configuration during extraction or evacuation, such as might occur during Stokes
litter evacuation of a casualty onboard
ship or in urban terrain. In this situation, a
patient who might have been maintaining
quite adequate cerebral perfusion while in
the supine position could suffer a catastrophic drop in pressure when placed in a
head-up position during evacuation. The
PASG, by providing external compression, could counter the hypotension
caused by venous pooling during a headup evacuation.
In a setting such as occurred during the
Afghanistan conflict in the 1980’s in
which the International Committee of the
Red Cross (ICRC) ran hospitals for the
wounded that were some distance from the
fighting in Pakistan, the wounded might
take many days to arrive. In such a situation it is certainly possible for wounds to
become infected and for septic shock to
occur prior to hospital treatment. It was
found in that during this conflict wounds
sutured in the field tended to putrefy 265
and in this kind of a setting septic shock
may be seen.
Anaphylactic Shock
Although anaphylactic shock can certainly
occur in the forward battle area from a
wide range of etiologies, it is exceedingly
unlikely that it would occur as a direct
result of enemy action so it will not be
discussed here beyond noting that it can
occur as a result of medications administered to combat casualties.
Thankfully septic shock is extremely rare
on the modern battlefield due to reasonably rapid evacuation of casualties. When
evacuation is much delayed, for whatever
reason, septic shock certainly can occur in
patients before they reach a hospital. Septic shock occurs when exotoxins (grampositive toxic shock) or endotoxins (gram
negative sepsis), enter the systemic circulation causing hypovolemia, cardiovascu-
Septic Shock
Although septic shock certainly may occur
in combat casualties it generally occurs
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Clifford C. Cloonan, MD
Circulation
sion. Hypoxemia from capillary leakinduced acute respiratory distress syndrome (ARDS) and pneumonia and/or
pulmonary aspiration, worsens the problem of hypoperfusion in septic shock.
Very large volumes of fluids may be required to resuscitate a patient in septic
shock. Fluid resuscitation should be continued until the mean arterial pressure is
above 60 mm Hg, urine flow is adequate,
and mentation is improving. Unlike most
other forms of shock in which inotropic
drugs that increase myocardial contractility and vasoconstricting drugs that increase systemic vascular resistance are
generally either useless or contraindicated,
in septic shock both may be helpful. Broad
spectrum antibiotics are indicated but the
management of septic shock in combat
casualties usually involves the excision of
necrotic and infected tissue so urgent
evacuation to a surgical facility is the most
important factor.
lar depression, and systemic inflammation.
Lipopolysaccharide’s, contained in the
cell wall of gram-negative bacteria, are
one of the major causes of septic shock
but gram-positive organisms can also
cause septic shock and recently there has
been a rise in the number of cases of sepsis in hospitalized patients caused by
gram-positive organisms.266, 267
Hypotension in septic shock results from
hypovolemia,
inflammatory-mediated
vasodilation, and cardiac depression. The
hypovolemia of septic shock is both absolute, from gastrointestinal volume losses,
sweating, and decreased oral intake, and
relative from capillary leak and third spacing. Inflammatory-mediated vasodilation
causes pooling of blood in the vascular
bed similar to that occurring in neurogenic
shock. Septic shock depresses cardiac
function even early in the course of septic
shock and eventually results in decreased
cardiac output further worsening hypoten-
Summary
that condition will expose the patient to
risk with little hope of benefit. Because it
is not possible to train prehospital personnel to make individual risk-benefit analyses at the point of wounding, their training
must be protocol driven and those protocols must be evidence-based.
The ability to prevent exsanguination and
to recognize and treat hemorrhagic shock
is fundamental to quality point-ofwounding care. The single most important
factor is the training of prehospital personnel of all skill levels. As important as
knowing what to do for the combat casualty, is knowing what not to do. It is especially important to emphasize to prehospital personnel, who are by nature actionoriented, that each medical intervention
carries with it some degree of risk. They
must also understand that the relative
value of each intervention varies with the
frequency of the condition(s) for which
the intervention(s) is/are being performed.
If a condition is unlikely to be present in a
patient, any intervention intended to treat
There must also be discipline in the system to ensure that the protocols are being
followed, and this requires some degree of
inspection and oversight. Today, unlike in
many areas of the civilian sector, care
provided by prehospital personnel in support of military operations is not monitored for quality assurance. In most instances, no one evaluates the medical decisions and interventions that are made at
57
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Clifford C. Cloonan, MD
Circulation
of shock, they should manage the patient
as if shock were present.
or near the point of wounding. This needs
to be done in both peace and war because
without such evaluation, real improvements in care are unlikely to occur.
Prehospital personnel must be able to recognize quickly and reliably the patient
who is in shock or likely to go into shock.
As noted above, this is no easy task. To
accurately diagnose shock, it is necessary
to integrate a wide range of data from
mechanism of injury, anatomic location of
wounding, general appearance and behavior of the patient, and physiologic data
gathered over time. As previously stated,
there is no single test that is pathognomic
for shock. Each of the generally recommended tests -- blood pressure, pulse, capillary refill, orthostatic vital signs, and
hemoglobin/hematocrit -- lack both the
sensitivity and specificity necessary to
reliably diagnose shock at or near the
point of wounding. In the proper setting,
an increase in both rate and depth of respirations and increasing thirst in a combat
casualty should be considered evidence of
shock until proven otherwise – the value
of these findings in diagnosing shock is
often under-appreciated.
The single most important treatment for a
patient in hemorrhagic shock is to stop the
bleeding – all bleeding if possible. All
else, in some instances even the airway,
are of secondary importance. Without hemoglobin to carry oxygen, a patent airway
is of little use. Hemorrhage control must
be achieved as quickly as possible, utilizing whatever technique or techniques are
both effective and medically and tactically
appropriate. Ideally, methods such as direct pressure, use of pressure points, and
elevation of bleeding extremities should
be attempted initially.
Immediate use of a tourniquet is indicated
if there is exsanguinating arterial hemorrhage in an extremity, or if the tactical
circumstances preclude the application of
less harmful, but more time and resource
consuming, methods. The continued need
for a tourniquet that has been applied as a
temporizing measure must be re-evaluated
at the earliest possible time and if other
methods are capable of controlling hemorrhage, the tourniquet should be removed.
The question of whether or not tourniquets
should be periodically loosened to allow
for some distal blood flow needs to be
studied, but the experience during World
War II was that this practice was implicated in enough combat deaths that it was
stopped. Unless good studies show real
benefit and unless training, procedures,
and new equipment can ensure that the
World War II experience with this practice
will not be repeated, it should not be advocated.
None of this is to suggest that any of the
other tests for shock lack value. Their
value lies in being used both in conjunction with other findings that would suggest
shock and in being used repeatedly over
time. When used to create a pattern or to
define a trend, these tests can effectively
be used to diagnose shock. Unfortunately
in many cases, the combat lifesaver, medic
or corpsman that is usually present at or
near the point of wounding often has neither the training, equipment, nor time to,
quickly and accurately diagnose shock.
Furthermore, the circumstances of combat
often render this impossible even when the
capability exists. This means that prehospital personnel must be taught that when
there is any question about the possibility
The non-pneumatic strap tourniquet (NSN
6515-00-383-0565) that has been in the
Army inventory since at least World War
II must be removed and replaced. How
many times is it necessary to prove that
this tourniquet is ineffective? Finding an
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Clifford C. Cloonan, MD
Circulation
as a saline lock that can be used for drug
and/or fluid administration as required.
Intraosseous access can be obtained either
through the medial malleolus with the
Bone Injection Gun (BIG®), the VidaPort®
system, or similar devices, or through the
sternum with the Pyng F.A.S.T. ® intraosseous infusion device or other similar device. These devices are generally easy to
use, and a properly trained person can obtain intraosseous access in under a minute.
Both drugs and fluids can be administered
through the intraosseous route, but because of the resistance to flow, fluids cannot be administered as rapidly through the
intraosseous route as through the intravenous route.
effective replacement should continue to
be a high priority medical research effort.
Prehospital medical personnel must be
trained to effectively apply tourniquets
and they must be trained to fully understand the risks and implications of tourniquet application.
Ancillary methods of hemorrhage control
such as the use of a dry fibrin sealant
dressing, QuikClotTM, the chitosin dressing, and/or the BioHemostat dressing may
significantly improve the ability of prehospital personnel to control hemorrhage
in a combat environment, but this needs to
be proven. Most importantly, enthusiasm
for these new hemorrhage control devices
should not cause prehospital personnel to
abandon conventional and proven methods
of hemorrhage control or to preferentially
use these new and, as yet, largely unproven devices. The reported case, during
Operation Iraqi Freedom, of a Marine with
a femoral artery injury, who was treated
with QuikClotTM first and then a tourniquet is most disconcerting. Although the
exact details of this incident are unknown,
it appears that QuikClotTM was used as the
initial hemorrhage control method, when
instead a tourniquet should have been applied. Unfortunately, the Marine died.
There is no way of knowing whether he
would have survived had the first intervention been to apply a tourniquet, but
given the available information it at least
seems possible.
The current recommended fluid resuscitation protocol promulgated by COL Holcomb for the AMEDD Center & School
91W Health Care Specialist program,
which is very similar to that recommended
by Beecher et al. in World War II 16 seems
reasonable and, in general, is supported by
scientific evidence. For patients with ongoing hemorrhage that is uncontrollable in
the prehospital setting, low volume, “hypotensive” resuscitation is recommended.
How low, for how long, remains to be determined. The key to survival in such patients is rapid evacuation to a location
where surgical control of hemorrhage can
be achieved.
Although Hextend® or any other similar
colloidal solution is recommended for
management of hemorrhagic shock, for
the reasons previously stated (weight and
cube issues primarily), this recommendation may not be optimum for the following
reasons:
After all controllable hemorrhage has
ceased, the next question is fluid resuscitation. Is it needed at all and if so, how
much and what kind? It is appropriate, for
a variety of reasons, that all combat casualties with more than trivial injuries have
vascular access established. Intravascular
or intraosseous access should be obtained.
Intravascular cannulation should be established with a short, at least an 18-gauge or
larger, catheter, and this should be set up
1. There is no scientific evidence that
these resuscitation fluids, when
compared with normal saline or
Ringers lactate, improve survival in
59
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Clifford C. Cloonan, MD
Circulation
hemorrhagic shock (in fact there is
some evidence to the contrary).
carrying, hemoglobin-based, resuscitation
fluids may prove effective in the treatment
of hemorrhagic shock on the battlefield.
This has yet to be proven but there is great
promise in these new fluids that minimize
or eliminate many of the risks and logistical difficulties associated with blood
transfusion while preserving oxygencarrying capability.
2. The efficacy and safety of these fluids in the management of dehydration of all causes (burn, heat injury,
gastrointestinal loss, etc…) and for
the treatment of other conditions for
which intravenous fluids might be
indicated (or used) is unknown.
The basic underlying defect in all forms of
shock is inadequate tissue perfusion. The
new solutions will be able to directly address this defect. It is hoped that the introduction of such a solution or solutions will
not have the same effect that the introduction of saline had in causing surgeons [or
in this instance, prehospital personnel] to
become cavalier about hemorrhage control. Kim Pelis, in her article, Blood Standards and Failed Fluids: Clinic, Lab, and
Transfusion Solutions in London, 18681916, notes that following the introduction
of saline to treat blood loss, “Surgeons,
with…unrestrained operative enthusiasm…spilled great quantities of blood
[that was] conveniently replaced with a
few to several pints of saline solution.”48
It is virtually certain that no matter how
good these oxygen-carrying solutions become, they will never be as good as the
patient’s own blood. Most assuredly, the
patient does best if his or her own blood is
retained, if not by preventing hemorrhage
in the first instance, then by returning it
into the circulation after it has been lost.
3. These colloidal solutions are very
expensive as compared to crystalloids. Because, in many instances,
aggressive fluid resuscitation of
combat casualties is now recognized
as ill-advised, the need to carry
large quantities of fluids is not as
great as previously thought, so the
weight and cube issue is, perhaps,
not as important as it was before.
However, because it is unlikely that
the selection of one intravenous
fluid over another will significantly
alter the survival of combat casualties, this should not be allowed to
become a contentious issue.
The question remains as to what role hypertonic saline dextran might play in the
management of combat casualties. Hypertonic saline dextran is currently being
evaluated in human trauma trials. Because
of its demonstrable ability to improve outcomes in head-injured patients, plus its
ability to rapidly expand the intravascular
bed when given through intraosseous access and when given in small volumes,
hypertonic saline dextran may ultimately
be the single fluid of choice in combat
casualty care. Unfortunately, many of the
same concerns raised about Hextend®,
Hespan®, and other colloidal solutions
apply to hypertonic saline dextran as well.
Until these concerns can be addressed
with good scientific studies, there should
be no rush to embrace this resuscitation
fluid. One or more of the new oxygen-
Autotransfusion of blood drained from
chest tubes appears to be done infrequently in most forward areas for a variety
of reasons. Given that this procedure is
demonstrably efficacious, relatively easy
to do, and logistically supportable, this
practice should probably be done more
often when clinically indicated. Finally,
there is the question of far forward administration of blood. The numerous
highly favorable comments about far for-
60
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Clifford C. Cloonan, MD
Circulation
cumstances of combat make it unlikely
that it will be possible to accurately estimate the percent of TBSA burn and even
if this could be done accurately by a combat medic in the heat of combat or during
evacuation it is unlikely, for a variety of
reasons, that it would be possible to accurately administer the calculated amount of
fluid. Most importantly, prehospital personnel need to know that seriously burned
patients need early and relatively aggressive fluid resuscitation and, unless there is
a contraindication (i.e. concomitant pulmonary blast injury and/or inhalation burn
injury) at least two liters of Ringers lactate
(or normal saline if Ringers lactate is not
available) should be administered quickly
and, if the evacuation is long, another liter
should be administered. If intravenous
access can’t be obtained, these fluids
should be given through intraosseous access. The total amount of administered
fluid must be recorded and this information transmitted to the receiving medical
treatment facility. As noted above, the
World Health Organization oral rehydration solution may be an option for use in
moderately burned combat casualties in
whom intravenous fluid is not possible for
any reason. Like badly burned patients,
patients in septic shock may require substantial volumes of fluid.
ward early administration of blood to
combat casualties during the Spanish Civil
War, World War II, and the Korean War
and the more recent favorable comments
about the near “miraculous” effect of
whole blood when used to treat casualties
in Mogadishu should give rise to questions
as to why blood is rarely used today forward of a surgical facility. There are most
certainly significant logistical and training
challenges to far forward blood administration, but surely these are no more onerous than in the past and certainly technological advances have made them less
so.
With regard to the management of types
of shock other than hemorrhagic, it seems
reasonable that only in the instance of
burn shock, and perhaps in the unlikely
instance of septic shock, should the abovedescribed recommended fluid resuscitation protocol be altered. Burn patients are
unique in that they have an ongoing fluid
loss that cannot be medically or surgically
controlled, and they require early, aggressive, and sustained fluid resuscitation. It is
probably of no major consequence, in
terms of outcomes, which of the generally
accepted fluid resuscitation formulas for
burns is used. Ringers lactate is the recommended fluid of choice for at least the
first 8 hours in all of the widely accepted
resuscitation protocols. In reality, the cir-
61
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Clifford C. Cloonan, MD
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Copyright 2007
The Brookside Associates, Ltd.
All Rights Reserved
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Clifford C. Cloonan, MD, FACEP
COL (ret) U.S. Army
Associate Professor
Deptartment of Military & Emergency Medicine
Uniformed Services University of the Health Sciences
Disability
If thou examinest a man having a dislocation in a vertebra of his neck, shouldst
thou find him unconscious of his two arms and his two legs on account of it, while
his phallus is erected on account of it, and his urine drops from his member without his knowing it; His flesh has received wind; his two eyes are bloodshot; It is a
dislocation of a vertebra of his neck.1(p 5)
The Edwin Surgical Papyrus
The British Admiral Lord Horatio Nelson, at the time of his greatest victory, the
defeat of Napoleon's fleet at Trafalgar in 1805, was mortally wounded by a gunshot to his chest that struck his thoracic spine and caused paraplegia below the
breast. Mr. Beatty, the ship's surgeon, was called and upon his arrival Nelson is
reported to have said, "Ah, Mr. Beatty! I have sent for you to say what I forgot to
tell you before, that all power of motion and feeling below my chest are gone and
you very well know I can live but a short time…You know I am gone." Mr.
Beatty's reply was: "My Lord, unhappily for our Country, nothing can be done for
you." Nelson died a few hours later.2
The Death of Lord Nelson by William Beatty
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Clifford C. Cloonan, MD
Overview and Epidemiology of Head
and Spine Injury
As reported by Picket et al. in their population-based study of brain injuries,3 blunt
head injury is a leading cause of death4
and disability in the United States.5 In the
United States roughly 1.5 million people
sustain a head injury each year and head
injury causes about 50,000 deaths annually.6 Of those with traumatic brain injury
[TBI] at least 80,000 are left with some
degree of long-term disability.7 Head
trauma in the U.S. is very costly generating roughly $346 million in emergency
care costs8 and $54 billion in associated
hospital care costs each year [in 1990 dollars].9
Despite its rarity, spinal cord injury is also
a significant contributor to health care
costs in the United States. Acute spinal
cord injury occurred in only 2.6% of the
114,510 patients entered into the Major
Trauma Outcome Study between 1982 –
1989.10 Within the U.S. only around
10,000 individuals sustain a spinal cord
injury (SCI) each year.11(p.329) Despite a
low annual rate because of the permanent
nature of cord injury almost 200,000 people in the United States have some degree
of paralysis caused by SCI.12 Annual aggregate costs, in 1988 dollars, for spinal
cord injury were estimated by Berkowitz
to be $5.6 billion.13
Combat-associated wounds of the head
and neck are also costly in terms of human
life, disability, and long-term cost. Such
injuries occur at a frequency greater than
would be predicted by body surface area
and cause a disproportionate number of
combat deaths. Although the head and
neck make up only about 9% of adult
body surface area, in the past 75 years,
roughly 17% of all combat wounds have
been to the head and neck. Head wounds
Disability
have accounted for around 14% of all isolated or major combat caused wounds14
and spine injuries make up about 2% to
3%.15
The relative frequency of combat-related
head and neck wounds varies considerably
depending upon the character of ongoing
military operations. During the Korean
War, for all types of combat operations,
injuries to the head and neck accounted
for approximately 20% of all wounds,
whereas during withdrawal operations,
only 13% of all wounds were to the head
and neck.16(p.44) These differences in frequency reflect differences in anatomic
exposure and variations in the type of
weaponry employed in different operations.16 (p.46) During World War II, of
14,000 battle casualties who survived long
enough to be treated in Fifth U.S. Army
hospitals, 6.17% had wounds involving
the
head
(excluding
maxillofacial
wounds). One-third of these wounds were
classified as intracranial and two-thirds
involved only the scalp; this reflecting the
high lethality of wounds that involve
penetration of the cranium.17(p.99)
One reason the head and neck are disproportionately injured is because combatants
frequently expose this part of their body to
engage the enemy. Some of this disproportionality may also be due to there being
a higher percentage of combatants with
minor head injuries who seek medical care
than occurs in those sustaining similar
wounds elsewhere on the body. Improvements in, and increased use of, body armor will certainly affect the total number
of casualties with head and neck wounds
occurring in a given combat engagement;
but there is currently no definitive evidence that shows this is occurring. Given
the vital structures contained within the
head and neck, it is not surprising that
combat-associated wounds to the head and
2
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Clifford C. Cloonan, MD
neck have a high incidence of morbidity
and mortality. Head wounds have accounted for almost half of all ground
combat deaths since World War II.18 During the Korean War, bullet wounds to the
head resulted in death 59.9% of the time
and fragment wounds to the head from
explosive devices caused death 37.7% of
the time.15 (p.44)
Head Injury
Despite significant advances in neurosurgery and critical care, penetrating head
wounds remain the second most common
cause of combat-related deaths (following
hemorrhage). Spinal cord injuries, particularly those in the cervical spine, although
rare, are also highly lethal. The case fatality rate for bullet-caused head wounds
during the Korean War was 14.7%; this
only being exceeded by bullet-caused abdominal wounds (14.9%) as a single cause
of death following hospitalization (the
category “body generally,” which covered
multiple causes and locations of wounds
that were otherwise not identified is listed
as the cause of death in 33% of all DOW
during the Korean War).16(p.44)
During the Korean War, the relative proportion of DOW from all causes was
25.4% for wounds of the head (for wounds
of the face it was 5.4%).16 (p.44) Overall,
major head wounds constitute about 14%
of all combat casualties. Of these, almost
50% die either immediately or shortly after wounding. Of the 50% who do not die
immediately, about 20% require advanced
medical care or they will die within 6
hours; without neurosurgical care another
30% will die within 24 hours. Most of the
remaining casualties with a major combatcaused head wound in which the dura has
been penetrated will die within a week of
wounding from infection unless properly
treated.
Disability
Thus, without timely and proper treatment, nearly 90% of all combat casualties
with serious head wounds involving penetration of the dura will die; even if such
treatment is immediately available, a significant number will still die.14 In Vietnam
20% of those with penetrating head
wounds who survived beyond the first few
minutes had very severe wounds and died
without surgery soon after admission. The
other 80% who survived long enough to
reach a hospital had surgery, with a mortality of about 10%. Fortunately, most of
these eventually returned to productive
lives.19 It is fortunate that a sizeable number of head wounds do not involve penetration of the cranium, because when
penetration occurs, death usually results.
Although head and neck wounds are still
associated with a high morbidity and mortality, the prognosis of casualties with
these injuries has improved considerably
in the past century. The mortality associated with all head wounds was 73.9% in
the Crimean War and 71.7% in the American Civil War.20, 21 In World War I, under
the guidance of the famous neurosurgeon,
Harvey Cushing, the DOW rate of penetrating head wounds, fell from 78% to
28.8% (keep in mind that this was in the
pre-antibiotic and pre-diathermy era).22, 23
When antibiotics were introduced during
World War II, the DOW rate for penetrating head wounds fell to 14%24 and during
the Korean War, to below 10%.16 (p.44),20, 25
The relative improvement in survival of
casualties with head and/or neck wound
seen during the Korean and Vietnam
Wars, as compared to earlier conflicts,
was most certainly even better than the
DOW rate would suggest because in both
of these conflicts, rapid aeromedical
evacuation of such casualties was routine;26 rapid transport of such casualties to
a hospital would be expected to cause a
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Clifford C. Cloonan, MD
paradoxical increase in the DOW rate because more casualties with unsurvivable
wounds live long enough to reach the hospital, only to die shortly thereafter.
In a study of 690 missile head wound
casualties of the Iran-Iraq war (19801988) who had dural penetration (which
occurred in 74% of all casualties with
head wounds),21, 27 Aarabi found that
72.1% of these wounds were caused by
shell fragments (mainly from shrapnel,
artillery, bomb, mine, hand grenade and
surface-to-surface missile) and 11.8%
were from gunshot wounds (mostly 7.62
bullets fired from AK-47 assault rifles). In
16.1% of cases, the wounding agent could
not be determined.28
Small fragments, not bullets, produce
most wounds in modern combat29 and bullets, being much more lethal than fragments, are much less likely to produce a
living casualty. This probably accounts, in
part, for the overwhelming predominance
of fragment, as opposed to bullet, wounds
of the head seen in combat medical treatment facilities. The Kevlar helmet effectively prevents penetration of most fragments but not most bullets (see following
discussion), so when it is used, the relative
percentage of bullet, as compared to fragment-caused head wounds (lethal and nonlethal) would be expected to increase.
Neck Injury
Penetrating wounds of the neck also have
a high morbidity and mortality. In a recent
study of 54 Israeli soldiers sustaining
penetrating neck wounds due to combattype mechanisms, 26% (14) died before
reaching the hospital and another 15% (8)
died after reaching the hospital, for an
overall mortality rate of 41%. Most of
these casualties sustained projectile
wounds (38) and gunshot wounds (13).30
Disability
Even in a civilian setting, overall mortality
due to penetrating neck trauma is as high
as 11%,31 and if there is injury to major
vascular structures such as the carotid or
subclavian vessels, mortality may exceed
60%.32
Of 4,555 cases in the WDMET database
of Vietnam casualties, 614 records were
coded as belonging to combat casualties
with some form of penetrating neck
wound (open neck wounds; superficial
neck wounds; open laryngeal injury; vascular injury of the head and neck; and spinal column injury, with or without cord
injury) for an approximate incidence of
13% of all combat casualties having some
type of penetrating neck injury.33 Because
of their relatively high lethality casualties
with penetrating neck wounds make up a
considerably smaller percent of the surviving wounded.
Injuries Involving the Spinal Cord
A survey conducted 1 month after D-Day
in World War II showed that about 10% of
all casualties who reached general hospitals were neurosurgical. Of all injuries in
casualties surviving to present for care,
head injuries accounted for about 4%, injuries to the spinal cord about 1.5%, and
peripheral nerve injuries 5–6%.34 (p82)
The history of Soviet medical care of spine injuries during World War II is illustrative of the influence that the tactical situation can have on the relative frequency of
the various causes of penetrating spine
injury in combat casualties and on wounding patterns. In the Soviet experience in
World War II bullet wounds caused on
average 42.5% of all combat-related damage to the spine, fragments caused 57.3%,
and blunt trauma caused only 0.2%. The
frequency with which each of these
mechanisms caused spine injury varied,
4
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Clifford C. Cloonan, MD
however, depending upon the tactical
situation. In defensive operations, fragment wounds made up a much higher percentage, whereas in offensive operations,
bullet wounds of the spine increased in
frequency.35(p45)
Disability
ences in the relative frequency of cord
injury and in the anatomic distribution of
spine injuries in casualties presenting to
hospitals. The preponderance of wounds
of the thoracic spine in surviving casualties was, at least in part, due to the fact
that those with penetrating neck wounds
were more likely to die prior to reaching a
hospital (selection bias).35 (p52)
Actually, despite noting a relative infrequency of cervical spine injuries, the published frequency in this text of such injuries was still 19.4%, with 38.7% occurring
in the thoracic spine, 35.8% in the lumbar
spine, and 5.7% in the sacral spine (it is
unclear from the Soviet text what injuries
accounted for the remaining 19.8%). What
was significantly different, however, was
that, as compared to those with other injuries of the spine, those with cervical spine
injuries rarely had wounds that penetrated
into the spinal canal. This was explained
in the Soviet text as being due to the fact
that those with cervical cord injuries
"…more frequently perished on the field
of battle."35 (p.55)
Flexion Teardrop, Unstable Fracture of C5, from
Operational Medicine 2001
Different types of penetrating injury were
also associated with different rates of associated spinal cord injury. Significant
injury was caused to the spinal cord more
frequently when the wounding agent was a
large fragment from an artillery shell or
bomb (unimproved munitions), whereas
there was less cord damage from smaller
fragments that produced "multi-fragment
wounds" of the spine.35 (p.46) Bullets would
also be expected to more commonly cause
spinal cord injury as compared to fragments from improved conventional munitions.
The tactical situation also caused differ-
Despite their infrequency among surviving
casualties, patients with spinal cord injuries often require significant medical resources, both initially and throughout their
lives. As noted by Frohna,36 in 1992 dollars, the average direct cost of caring for a
ventilator-dependent patient with a high
cervical spine injury was $417,067 for the
first year and $74,707 for each subsequent
year.37(p.1-5)
These are very debilitating injuries, so
efforts to minimize cord damage wherever
and whenever possible are certainly reasonable and appropriate. The great majority of combat-caused head and neck
wounds continue to be penetrating, but as
the total number of U.S. casualties caused
by direct enemy action has declined the
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Clifford C. Cloonan, MD
relative frequency of blunt trauma from
motor vehicle and aircraft crashes and
from falls has likely increased. As of June
2003, accidents of all causes had accounted for 37% of all Operation Iraqi
Freedom fatalities, and almost half of
those were due to vehicular accidents.38
For this and other reasons, it is important
to review how such injuries are managed
at or near the point of injury in civilian
and battlefield settings.
Disability
Even blunt spinal trauma in combat may
be different from civilian blunt trauma.
Combat casualties may suffer spine injury
due to mechanisms such as ejection from
high-performance aircraft and aircraft accidents, which either do not occur at all in
civilian settings or occur much more
rarely. The environment in which these
injuries are cared for is also significantly
different.
The exact impact of these differences on
the frequency of unstable fractures is unclear, but it is likely that the frequency of
unstable fractures among combatants with
cervical spine injuries is different than that
in a random mix of civilian patients with
cervical spine injuries. These differences
alter the relative risk-benefit ratio of any
care provided to combat casualties such
that a medical practice that might produce
more good than harm in a civilian setting
might well have the opposite effect in a
combat environment.
Flexion Teardrop, Unstable Fracture of C4, from
Operational Medicine 2001
Much of how we care for patients with
head and spine injuries in combat today
comes from civilian practice, so it is important to understand that medical practices appropriate in a civilian setting may
not always be appropriate in a combat environment. There are significant differences in combat mechanisms of injury as
compared to injury in civilian settings.
To understand how modern prehospital
care for head and spine injuries has come
to be what it is, it is important to examine
the epidemiology of civilian head and spine injuries and to consider the modern
civilian prehospital practice environment.
Within the civilian population approximately 11% of all trauma admissions have
a head injury39 and 1-3% of all blunt
trauma victims with cervical fractures40, 41
have an injury to the spine [spinal cord].
According to the American College of
Surgeon's ATLS course, approximately
55% of spine injuries occur in the cervical
region, 15% in the thoracic region, 15% at
the thoracolumbar junction, and 15% in
the lumbosacral area.42
Blunt trauma, primarily from motor vehicle accidents, accounts for approximately
82% of all serious non-fatal civilian head
injuries (Traumatic Brain Injury in the
6
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Clifford C. Cloonan, MD
United States: A Report to Congress CDC
Estimates of Traumatic Brain InjuryRelated Disability Current Data @
http://www.cdc.gov/doc.do/id/0900f3ec800101e6/)
and a
similar percentage of all civilian spine
injuries.36 In civilian trauma, only around
15% of all spine injuries43-45 and approximately 10% of all head injuries (Traumatic Brain Injury in the United States: A
Report to Congress CDC Estimates of
Traumatic Brain Injury-Related Disability
Current
Data
@
http://www.cdc.gov/doc.do/id/0900f3ec800101e6/) are
caused by a penetrating mechanism, most
of these being the result of a low-velocity
gunshot wound from handguns.
A number of articles have placed the frequency of spinal column injury from gunshot wounds to the neck (primarily low
velocity) from a low of 2.7%46 to a high of
22%47 with neurological deficits being
present in 1.9%.46, 47
Civilian vs. Military Spine Injuries
The above discussion about epidemiology
of wounding is relevant to a discussion
about point-of-wounding care for casualties with spine injuries. When making
risk-benefit decisions about the care of
such patients, it is necessary to know, at
least approximately, the portion of surviving casualties who will have spinal cord
and unstable cervical spine injury. The
benefit of reduced risk of spinal cord injury must be balanced against the logistical challenges and the risks associated
with spine immobilization in a combat
zone; the outcome of this analysis is substantially influenced by the incidence of
unstable spine injuries in combatants. The
more common unstable spine injury is in a
given population the greater the relative
benefit of spine immobilization.
The estimate by Arishita et al.33 of an in-
Disability
cidence of 1.4% unstable penetrating cervical spine injuries in combat casualties
with penetrating neck wounds is significantly influenced by how many casualties
with potentially unstable cervical spine
injuries died prior to treatment. In their
analysis 20 of 365 [5.5%] combat casualties who had potentially survivable penetrating neck wounds, died. If these 20
casualties had been included in Arishita et
al.’s estimate of unstable spinal cord injury, the frequency of unstable cervical
spine injuries among those who do not die
immediately could be more than twice as
high (3.7%).48
However, unless it becomes significantly
easier in the future to reach and treat combat casualties with penetrating neck
wounds, there will always be a group of
patients who will die before they receive
care; this fact must be considered in any
risk-benefit analysis of medical care.
In the article by Arishita et al.,33 the case
of a soldier shot through the neck and
found lying face down in the water is illustrative. This casualty was dragged out
of the water by his comrades without any
regard for his cervical spine, and was later
found, on autopsy, to have an unstable
cervical spine injury with cord damage.
This individual was described by the authors as someone who might potentially
have benefited from cervical spine immobilization, when in fact it seems probable
that if the casualty were not already paralyzed, he would have removed his own
face from the water. Had care not been
almost immediately available, it is highly
likely that this casualty would have died at
the site of wounding from exsanguination
or drowning, rather than later. Thus, the
fact that his cervical spine was not immobilized in the middle of a firefight seems
not to be especially relevant.
Injury to the head and neck from frag-
7
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Clifford C. Cloonan, MD
ments is quite rare in a civilian setting but
is relatively common on the battlefield.
The great majority of civilian bullet
wounds are caused by low-velocity handguns, whereas most bullet wounds to the
head and neck sustained during combat
are caused by high-velocity weaponry,
with low-velocity bullet wounds being
rare in combat. These differences in
mechanism of penetrating trauma make it
difficult to compare penetrating neck
trauma in civilian and military settings.
The frequency of cord injury and spine
instability is certainly different between
wounds caused by high-velocity, fullmetal-jacket rounds and those caused by
soft-lead, low-velocity bullets shot from a
handgun. An extensive discussion of these
differences is provided later in this chapter.
Another difference between civilian and
military head and neck trauma is that the
great majority of combatants are healthy
males between the ages of 18 and 35,
whereas the civilian population includes
both the very young and the very old: two
groups of patients with a much higher risk
of head and neck injury and of spine instability.
Different age groups even have different
patterns of injury. In infants and small
children, the head is relatively much larger
than the neck and body as compared to
adults, and the supporting musculature is
much weaker, making certain injuries considerably more likely. On the other end of
the age spectrum, degenerative changes
predispose the elderly to spine and spinal
cord injuries. In both the very young and
the elderly, high cervical spine injuries are
relatively more common compared to
those in the age range of most combatants
(18-35), in whom injuries to the lower
cervical spine predominate.
In the multicenter National Emergency X-
Disability
radiography Utilization Study49 (NEXUS)
participants between 20 and 30 years of
age sustained their injury between the levels of C5 and C7 around 50% of the time
and the vertebral body was the structure
fractured in roughly 30% of these lower
cervical vertebrae – making it the single
most commonly injured structure.50 Importantly isolated vertebral body fractures
are rarely associated with spinal cord injury.50 In the 20- to 30-year old age group,
spinal cord injury occurred in only 4.1%
of patients with a radiologically significant cervical spine injury.51, 52 In the 60- to
80+ age range, however, fractures of C1
and C2 accounted for 57% all fractures.51
A high percentage of C1-C2 fractures are
unstable. In NEXUS, the relative risk for
cervical spine injury in elderly blunt
trauma victims was 2.09, compared to
0.87 for other adult blunt trauma victims.52
All this suggests that the risk of spinal
cord injury and spine instability is probably considerably higher in a civilian population that includes an elderly population
than in combatants, nearly all of whom are
young, previously fit, adults.
Definition of “Instability”
Before discussing the frequency of spine
instability in blunt and penetrating injuries, it is important to define exactly what
constitutes "instability." The term, "unstable fracture" is commonly used in the literature without there being general
agreement as to exactly what this term
means. Guttmann, in his 1976 text, Spinal
Cord Injuries: Comprehensive Management and Research, 53 (p179) noted that,
"There is still disagreement as to the definition of stable and unstable fractures,
and the criteria used differ considerably."
Because fear of causing spinal cord injury
in a neurologically intact patient who has
an “unstable” spine injury has led to the
8
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Clifford C. Cloonan, MD
current, nearly universal, practice of spine
immobilization, it is important to define
exactly what constitutes an "unstable" injury. Unfortunately, most investigators do
not provide a definition when they use the
term "unstable." Without an agreed-upon
definition, it is not possible to do an accurate meta-analysis of studies to determine
the true frequency of this condition. Given
the rarity of unstable cervical spine injury,
it is difficult to do a large enough study to
determine its true incidence.
Instability is generally defined by the
anatomic structures that are injured.54, 55
White et al. performed an analysis of the
clinical stability of cadaveric spines following sequential transection of the anterior and posterior structures (ligaments,
annulus fibrosus, and articular facets), in
flexion and extension, to determine which
of these structures contributes most to spinal stability.55 They found that the spine
tends to remain stable even when most of
the ligaments are transected.
They also found that when instability occurred in this model, it occurred suddenly
and completely, without any warning of
intermediate instability. With regard to the
influence of the paracervical muscles on
spinal stability, White et al. stated that,
"Although muscles exert some forces, we
do not believe that they play a significant
role in clinical stability.” They based this
conclusion upon the clinical observation
that in “severe motor paralysis of the
paracervical muscles, significant displacement of the vertebral bodies and facets does not occur provided the bone and
ligamentous structures remain intact." Obviously because their study used cadaveric
spines, they could not test this hypothesis.
In any case, it should be noted that the
converse situation is the issue in most patients; i.e., when the bone and ligamentous
Disability
structures are NOT intact, how much do
the paracervical muscles contribute to stability? No study to date has assessed this
important question, although this author is
aware of unreported anecdotes that suggest that patients with unstable cervical
spine injuries are, at least occasionally,
able to stabilize their cervical spines
through the use of paracervical and other
muscles (reports of patients presenting to
emergency departments stabilizing their
own highly unstable cervical spine fractures with their hands “holding their head
on”).
Spine instability is occasionally defined
functionally as well as anatomically.
Hockberger et al., in Rosen's Emergency
Medicine: Concepts and Clinical Practice
text, state that if neurological injury has
occurred, particularly delayed neurological injury, then, by definition, the original
injury was "unstable."56(p372) They note
that the concept of stability is "…complex
and somewhat confusing" and that mechanically stable injuries may be associated with spinal cord injuries (this is certainly the case in penetrating trauma)
whereas many patients with mechanically
unstable injuries may have no neurological deficit.
Generally anterior column injuries, i.e.
those involving only the vertebral body
and/or intervertebral disks, are considered
stable. Injuries of the posterior column
(pedicles, transverse processes, articulating facets, laminae and spinous processes,
together with their associated ligaments)
are more likely to be unstable, especially
if there is some degree of dislocation with
associated ligamentous injury. Isolated
fractures of posterior elements without
dislocation have a relatively low incidence
of associated neurological injury.
The most unstable of all injuries are those
9
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Clifford C. Cloonan, MD
involving elements of both the anterior
and posterior columns.50 In an extensive
epidemiologic study by Riggins & Kraus,
patients with isolated vertebral body fractures had a 3% incidence of neurologic
deficit, whereas those sustaining fractures
of the posterior elements and body with
some degree of associated malalignment
of the spine had an incidence of 61%.51
Guttmann, in his Spinal Cord Injuries text,
notes that data on the frequency of unstable spine injury vary considerably from as
low as 3.5% to as high as 12%.53
Influence of Mechanism of Injury on
Spine instability
It is unclear whether a fracture caused by
blunt force is the same as a similar fracture caused by a penetrating mechanism in
terms of spinal stability. It is likely that
blunt trauma and penetrating trauma are
quite different in this regard. The kinetic
energy transferred to the spine and its associated structures during a motor vehicle
or aircraft accident or during a fall from a
height is considerably different than that
transferred during penetrating injury. In
penetrating injury, the kinetic energy of a
bullet or fragment is expended within a
relatively small space, whereas in blunt
trauma, the kinetic energy is spread over a
much larger area.
The rate of energy release is also different.
In high-velocity penetrating injury, all of
the kinetic energy is released into the tissue within microseconds. In blunt force
injury, the transfer of energy is relatively
much slower. These differences in energy
magnitude, distribution, and transfer time
are probably important in terms of likelihood of spine instability.
Many authors have stated that bullets
Disability
cause spinal cord injury from "direct
trauma" rather than from movement of an
unstable spinal column after the initial
injury.57-60
Many factors may contribute to the observed differences but it appears that spine
instability is considerably less common
when the mechanism of injury is penetrating. It is therefore probably erroneous to
assume that the degree of spine instability
present in a patient with a fracture caused
by blunt force would be the same in a patient with an identical fracture caused by a
penetrating mechanism.
Barkana et al. note that all of the literature
concerning definition, description, and
experiments of spine instability is based
on blunt trauma.30, 61-67 They go on to
comment that when penetrating injuries
are evaluated, it is very rare to find unstable injury, and they state that it is
"…conceptually impossible for a penetrating injury to cause such substantial spinal
damage leading to instability without
completely destroying the cord."30 It
should be noted that this Israeli study by
Barkana et al., and their collective experience, is probably influenced by a predominance of penetrating injuries caused
by high-velocity military bullets.
Apfelbaum et al. describe a case of “unstable” cervical spine injury without cord
damage caused by a 22-caliber long rifle
bullet fired from a handgun.44 Although
this patient’s spine may have met an anatomic definition of “instability,” the functional “instability” of even this injury is
disputable. This patient did not sustain a
spinal cord injury despite periods of time,
both before and after receiving medical
attention, in which her cervical spine was
not immobilized. During the time her
spine was not immobilized there was quite
probably movement that would have
10
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Clifford C. Cloonan, MD
caused cord injury had there been significant instability; it is certainly unlikely that
a patient who had been shot in the neck
would lie perfectly still while waiting for
the ambulance to arrive. Low-velocity
bullets and fragments certainly can cause a
spine injury that fits the commonly used
anatomical definition of "unstable" without causing concomitant cord injury even
when movement occurs.
Although current literature suggests that
the risk of an unstable cervical spine following penetrating trauma is minimal,33, 56
there is little data to support this statement. In their retrospective review of
cases in the WDMET report with penetrating neck wounds, Arishita et al. conclude
that the risk of an unstable cervical spine
injury is very low in combat casualties.33
Only one study has looked specifically at
the frequency of cervical spine instability
in penetrating trauma, and it concluded
that "spinal stability following a gunshot
wound is not guaranteed, especially in the
cervical spine, and each case should be
assessed individually for the presence of
instability"(see earlier discussion).58 No
study in the current literature, however,
contains a side-by-side comparison of
overall morbidity and mortality associated
with management of penetrating neck with
immobilization vs. no immobilization. For
many reasons it is quite unlikely that such
a study will ever be done. Only recently
have multicenter trials begun to compare
different approaches to the management of
patients with blunt cervical trauma.67
Isiklar & Lindsey58 retrospectively evaluated patients with low-velocity gunshot
wounds to the spine who presented to a
civilian facility. Of 12 cases of gunshot
wounds involving the cervical spine, 3
(25%) were described as "unstable." In
this study, clinical stability of the subaxial
cervical spine was defined “according to a
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scoring system developed by White &
Panjabi,” and described as
…a quantitative analysis of the behavior of the spine as a function of the
systematic destruction of various
anatomic elements. Under controlled
conditions designed to maintain the
biological integrity of the specimens,
17 motion segments from 8 cervical
spines were analyzed. The spines were
studied with either flexion or extension simulated using physiologic
loads.”69
In the Isiklar and Lindsey study, 11 (92%)
patients had neurological deficits, and 8
(67%) had related vascular injuries. Only
1 patient (8%) had an unstable cervical
spine without a neurological deficit.58 In
order to assess cervical spine instability in
the manner described by White et al.,68 it
would have been necessary for Isiklar and
Lindsey to perform flexion and extension
of the cervical spine to determine whether
there was > 3.5 mm of linear intervertebral
displacement and/or > 11o of angular displacement. There is no evidence in their
retrospective record review that this is
how cervical instability was determined;
in fact, the contribution of bony injury to
instability was not considered.58 This
brings into question how cervical spine
stability was assessed in this study and
suggests that this study can’t be used to
estimate the frequency of spine instability
in penetrating neck trauma.
High-velocity bullets tend to cause "all-ornone" injuries in the neck. If no vital
structures are hit, they may pass through
the neck causing little damage, but if the
spine is struck (excluding the tip of a
spinous or transverse process), the damage
tends to be catastrophic, with immediate
quadraparesis and, often, death.
This “all-or-none” phenomenon tends also
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Clifford C. Cloonan, MD
to be true for high velocity gunshot
wounds to the head. Where low-velocity
handgun bullets may penetrate the skull to
cause neurological damage, but not death,
such an event rarely occurs in casualties
sustaining high-velocity gunshot wounds
to the head.
Apfelbaum et al.44 make the observation
that lower velocity, smaller caliber handguns are associated with a different injury
pattern58, 63, 70 than previously seen in military studies,33 including an increased frequency of fracture without neurological
impairment and increased associated vascular injury. They postulate that one reason for the increased incidence of cervical
spine instability with low-velocity gunshot
wounds may be, "…the decreased amount
of surrounding soft tissue [in the neck],
compared to the thoracic or lumbar spine,
such that an increased amount of the bullet's kinetic energy is conveyed to the spinal column with increased skeletal injuries."58
Although this mechanism may partially
account for the higher incidence of cervical, as compared to thoracic or lumbar,
spine instability, another explanation is
more likely. Most studies assessing spine
instability have been done on admitted
patients and do not assess spine instability
in nonsurvivors. Such studies therefore
fail to identify the most likely explanation
for the low incidence of spine instability
among survivors of such wounds, i.e., that
most patients with gunshot wounds who
have a spine injury severe enough to produce instability also sustained injury to
critical structures that lead to rapid death
(Since a high velocity bullet is more likely
than a low velocity bullet to kill it’s victim, a patient with a low velocity bullet
wound is more likely to survive with an
unstable spine injury; thus since only survivors tend to be assessed for the presence
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of spine instability those with low velocity
GSW appear to have a higher incidence of
unstable fractures).
It is clear, therefore, that the mechanisms
causing civilian head and neck trauma,
even when comparing blunt with blunt and
penetrating with penetrating injury, are
different in ways that should impact on
management decisions because each has a
different likelihood of causing an unstable
spine injury in a surviving casualty. It is
also clear that, in a combat setting, where
there is often a persisting risk of death and
injury both to the casualty and to anyone
attempting to rescue and treat the casualty,
the risk-benefit ratio of any procedure(s)
that might be done is also affected. In the
WDMET database one of every ten casualties was wounded or killed while attempting to render aid to another casualty.
33
Selection Bias
The true incidence of instability in blunt
and penetrating spinal trauma is difficult
to ascertain because of selection bias. The
great majority of studies that address the
question of spine stability have been performed by neurosurgeons. Patients treated
by neurosurgeons, however, have a higher
incidence of instability because, in many
cases, concerns about instability led to
their being referred to a neurosurgeon in
the first place.
Frequency of Spinal Cord Injury and
Instability in Penetrating Trauma
Barkana et al.30 note that in a study done
by Hammoud et al.71 of spinal cord injuries during the Lebanese civil war, none of
the 24 injuries reported had spine instability. They go on to say that spine instability
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Clifford C. Cloonan, MD
occurs very rarely in spine injuries from
fragments and bullets because the bone
architecture is only a little disturbed. Despite a statement by Yoshida et al. in their
article on gunshot wounds to the spine
that, "With few exceptions [gunshot
wounds to the spine] result in a spinal
cord injury,"72 in fact, this is not the case.
More importantly, among those who survive the initial injury (which is the only
population of medical concern) the percentage of patients with gunshot wounds
to the neck who also have an injury to the
spine is in the 5 to 20% range.30, 33, 47, 73-75
Although there may be a higher incidence
of associated spinal cord injury in penetrating spinal trauma as compared to blunt,
the fact remains that overall spinal cord
injury is uncommon in this group, especially if only those who survive the initial
injury are considered.
The writings of Sir Zachary Cope, based
on his and others’ experiences during
World War II, seem to agree with Barkana
et al.30 that damage to the spinal cord by
high-velocity missiles is generally caused
by direct trauma, not by spine instability
that later produces spinal cord damage.
Cope noted that:
…the stability of the spine was not
much endangered by a shell fragment…small pieces of metal moving at
high velocity were the usual wounding
agents [during World War II]. These
did damage by penetration or by traversing the body but they did not very
often shatter the spine…[not] all of
these wounds appeared to result in total and lasting paraplegia. Recovery
seemed possible in about 25-30 percent of cases.76(p381)
Although concern for patients is the primary factor that has shaped current civilian EMS, guidelines regarding the prehos-
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pital management of patients with head
and neck injuries, fear of litigation, and
dogmatic adherence to practices that lack
scientific evidence of efficacy have also
played a role. These issues will be discussed in detail below in the section on
spine immobilization.
Diagnosis
Although medical personnel at or near the
point of wounding have, for many reasons,
a limited ability to make specific diagnosis
in patients with head and neck trauma, a
degree of diagnostic certainty can often be
achieved. Despite the challenges, it is important to be as diagnostically precise as
possible in the forward areas for the following reasons:
1. Diagnostic accuracy can considerably improve patient management at
or near the point of wounding. If it
is reasonably clear what the patient's
diagnosis is, or perhaps more importantly, what it is not, then treatment
can be focused on those who will
benefit most from it. In forward areas, a focus on diagnostic accuracy
also allows the most efficient use of
limited staffing and equipment resources.
2. An accurate diagnosis is essential to
making proper evacuation decisions.
Combat casualties with unmistakable neurological injury or an unstable spine should be evacuated to the
care of a neurosurgeon once they are
clinically stable and as soon as logistically possible. Early access to a
neurosurgeon has been associated
with improved outcomes for patients
with serious head and spine injuries.77(p.177)
Clues to a patient's diagnosis can be ob-
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Clifford C. Cloonan, MD
tained by ascertaining an accurate mechanism of injury. This can often be accomplished by simply asking the patient what
happened. Patients who are conscious and
able to speak can often describe the exact
mechanism of injury and can frequently
describe their symptoms in terms that allow for an accurate diagnosis. The challenge is to be able to accurately interpret
what the patient has said and to use that
information to make the proper diagnosis.
A rapid physical examination can also
provide critical clues. Most importantly,
care providers at or near the point of
wounding must maintain a high index of
suspicion for serious head and neck
trauma, because the effect of a missed diagnosis can be catastrophic. The focus of
the following discussion will be on the
diagnosis of spine injury and unstable
spine injury. Head injury diagnosis and
management is discussed later. Although
it is not possible, at or near the point of
wounding, to diagnose spine instability
with certainty (indeed this is difficult to do
even in a fully equipped hospital) it is possible, primarily by knowing the mechanism of injury, to roughly determine the
probability of spine instability.
Clearing the Cervical Spine at or near
the Point of Wounding
A major current area of discussion and
controversy in civilian emergency medical
services is the "clearing" of patients with
potential cervical spine injuries prior to
transport, allowing prehospital personnel
to exercise judgment as to which patients
with possible spine injury actually need to
be immobilized. This civilian controversy
is primarily fueled by
(1) The costs associated with placing a
high percentage of trauma victims
into cervical spine immobilization
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(estimated at $75 million annually
within the United States)36 and
(2) The risks associated with cervical
spine immobilization. This issue of
cervical spine immobilization will
be discussed later when the treatment of patients with known and potential spine injuries is discussed.
How capable are prehospital care providers at accurately sorting determining
which patients do and do not have spine
injury, particularly unstable spine injury?
As Hoffman et al. point out, an assessment
for spine injury could be almost 100%
sensitive if every casualty with even a remote possibility of spine injury were presumed to have such an injury.78 Unfortunately, such an approach in a military setting would cause substantial overevacuation, would create a significant
burden on care providers, and would expose a large population of casualties without spine injury to the risks of spine immobilization (discussed below).
For these reasons, it is essential that a reasonable degree of specificity be obtained.
So, what evidence is there that prehospital
care providers can accurately identify
those with spine injuries? More importantly, how able are they to identify those
who may suffer adverse consequences if
there were an error in diagnosis, i.e. patients whose spines are unstable and those
who must be treated by a neurosurgeon?
There are certainly some spine injuries
(some spinous and transverse process fractures, and some compression fractures for
example) that, if missed, will result in no
adverse consequences to the patient.
As part of the large multicenter National
Emergency X-Radiography Utilization
Study (NEXUS), prospective data were
collected on cervical spine injuries.78 One
part of this study involved prospective
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Clifford C. Cloonan, MD
assessment of the efficacy and safety of
selecting patients with a very low probability of cervical spine injury for treatment not involving spine immobilization
or radiography. The instrument used to
make this determination is the NEXUS
cervical spine criteria; i.e., patients with
none of the following criteria were
deemed to be safely not immobilized or
radiographed:
•
A focal neurological deficit
•
Any evidence of intoxication
•
Any tenderness at the posterior midline of the cervical spine
•
•
Any painful injury that might distract the patient from the pain of a
cervical spine injury
Any alteration of consciousness
from any cause
(The first four criteria demonstrated high
inter-rater reliability in a study of blunt
trauma patients assessed for cervical spine
injury that was published in the same
year.)80 The Canadian C-Spine Rule, developed for the same purpose, uses the
following criteria to decide which trauma
victims need cervical spine radiography.81,
82
By these guidelines, no cervical spine
radiographs are indicated in alert and stable trauma victims if:
(1) There is no high-risk factor, including
a. Age >64
b. Dangerous mechanism (fall >
3 feet, axial load to head [e.g.,
diving], motor-vehicle crash
at > 100 km/hour and/or involving rollover and/or ejection from vehicle, motorized
recreational vehicle crash, or
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bicycle crash), or
c. Paresthesias in extremities
(2) And if there are indications of low
risk such as
a. Simple rear-end motorvehicle crash
b. Patient in sitting position in
emergency department
c. Patient ambulatory at any
time
d. Delayed onset of neck pain,
and
e. Absence of midline cervical
tenderness
(3) Patient is able to actively rotate neck
45 degrees to right and left.
Both the NEXUS and Canadian C-Spine
Rule studies only assessed the efficacy
and safety of their decision instrument
when applied by physicians. Some authors
have studied whether emergency medical
services providers could apply an identical
or similar instrument to make decisions
about spine immobilization at or near the
point of injury.
Brown et al. conducted a study comparing
the application of the NEXUS instrument
by EMS providers and emergency department physicians. The emergency physicians and the EMS providers were
blinded to each others’ assessments. There
was 78.7% agreement. In only 7.7% of
cases, the emergency physician indicated
that the patient should be immobilized
when the EMS assessment did not. In general the EMS provider's assessments were
more conservative than those of the emergency physician's.83 Unfortunately, this
study does not provide any evidence as to
the safety and efficacy of having EMS
providers use the NEXUS guidelines to
avoid immobilization.
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Clifford C. Cloonan, MD
Stroh et al. conducted a retrospective assessment of a prehospital protocol for outof-hospital spine clearance that was used
on 42,000 patients in Fresno County, California.84 The charts of all patients (N=861)
discharged from five Fresno County
trauma centers with the diagnosis of “significant” cervical injury were examined.
EMS personnel brought in 504 patients, of
whom 495 (98.2%) had cervical spine
immobilization in place. Of the remaining
9 patients, 2 refused immobilization and 2
could not be immobilized; 3 cervical spine
injuries were missed by the protocol criteria and 2 were missed because of protocol
violations. Of the 5 patients with injuries
who were not immobilized, 1 had an adverse outcome and two had injuries that
were considered unstable. The three patients missed by the protocol were at extremes of age: 9 months, and 68 and 83
years. Further, the two missed patients
who were considered protocol violations
were elderly (73 and 76 years of age),
which suggests that cervical spine injury
in infants and the elderly may be more
difficult to ascertain in the prehospital setting (note that this is not an issue in military combatants).
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protocol really lead to meaningful selective immobilization?” As noted above,
immobilizing everyone would produce a
sensitivity of 100%. Unfortunately, there
is no way to calculate the specificity of the
Fresno approach or to know whether, or to
what degree, EMS personnel in the Fresno
study were able to reduce unnecessary
immobilization among patients with blunt
trauma.78 This is certainly the important
issue because one of the primary objectives of any prehospital cervical spine injury clearance protocol must be to safely
minimize the number of unnecessary immobilization procedures.
Finally, although the complexities of the
issues raised and the resources that would
be necessary to prospectively determine
which patients require immobilization
make it unlikely that a definitive answer
will ever be found, the following points
(elucidated by Hoffman et al.) should be
kept in mind:78
(2) Chart reviews are subject to substantial biases and errors, even when done
rigorously.85
(1) Any out-of-hospital protocol should
emphasize safety (sensitivity) over
efficiency (specificity). The cumulative small benefits associated with
avoiding spine immobilization in
many patients without injury must
be balanced against the rare but extremely important harm associated
with failing to immobilize injured
patients. [It should be noted however that the "cumulative small
benefits" have never been well
quantified (see following discussion
about the risks of cervical spine immobilization) so it is not possible to
know the true extent of benefit that
might be derived from a selective
immobilization protocol.]
One of the most important questions
raised by Hoffman et al. is, “Did the use
of the prehospital spine injury clearance
(2) Decision instruments proven to be
effective in the hands of emergency
physicians should not be assumed to
Hoffman et al. in their review of the Stroh
study,78 offer the following words of caution about this study:
(1) For a variety of reasons, the actual
sensitivity of the EMS practice in
Fresno for immobilizing patients with
cervical spine injury may well be
much lower than reported and
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
work equally well when applied by
others (eg, paramedics or nurses),
especially in a very different (outof-hospital) environment [certainly
a true statement that applies to all
procedures].
(3) Any out-of-hospital cervical spine
clearance protocol that is created
should incorporate those elements
with the best face validity (Is there
neck pain? Did the mechanism involve forces that could possibly hurt
the spine?), as well as elements
from any protocols that have been
proven to be useful in the ED. The
number of patients immobilized by
EMS should probably end up
somewhat higher than the number
radiographed in the ED.78
Probability of Spine Injury in
Patients with other Injuries above the
Clavicle
The American College of Surgeon's Advanced Trauma Life Support (ATLS)
course states that, "Any injury above the
clavicle should prompt a search for a cervical spine injury.” According to ATLS
approximately 15% of patients sustaining
such an injury will have an actual c-spine
injury and approximately 5% of headinjured patients have an associated spine
injury. 42 (p217)
Others also consider the presence of head
or facial injuries to be an indication for
cervical spine radiography.86, 87 The rate of
cervical spine injury in facial trauma series varies from 0% to 4%.88 Bayless et al.
reviewed 1382 cases of mandibular fractures and found cervical spine injuries to
be rare.89 They concluded that history and
physical examination, without radio-
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graphic studies, are sufficient to evaluate
the alert, cooperative patient with blunt,
low-velocity mandibular trauma and no
other complicating features.
Other reports36, 90, 91 have confirmed the
low incidence (1.04% and 1.8%) of cervical spine injuries in patients with facial
trauma. Williams et al. reviewed the records of 5,021 trauma patients and found
that there was no higher incidence of cervical spine injury in head- injured patients,
in patients with facial trauma, or in patients with clavicular fracture than in those
without.92 If the Glasgow Coma Scale
(GCS) was used to stratify head-injured
patients, a higher incidence of cervical
spine injury was noted in patients with a
GCS < 14 than in those with a GCS > 14.
Hills and Deane reviewed a series of 8,285
blunt trauma victims and found that facial
injuries were not associated with cervical
spine injuries;93 however, they found a
much greater risk of cervical spine injury
in victims with “clinically significant”
head injury. In another study by Bayless et
al., of 228 cases of blunt head trauma,
only 3 were found to have cervical spine
injuries for an incidence of 1.7(3)% [Note
that 3/228 = 1.3% while 4/228 = 1.7% but
original article states incidence is 1.7%].89
However, when only those patients with
serious head injury (more than a mild concussion) were considered, the frequency of
cervical spine injury in this study rose to
5%. It is not surprising that in patients
with evidence of serious head trauma,
there is a significantly higher incidence of
cervical spine injury.
A recent study by Patton et al. has some
relevance to the care of combat casualties.
In this study 102 individuals sustaining a
blunt assault to the head and neck region
were evaluated, but no clinically significant cervical spine injuries were detected
17
Immediate Care of the Wounded
Clifford C. Cloonan, MD
(there was one patient with a spinous
process fracture who had been hit in the
back of the neck with a pipe – not clinically significant).94
Also of military relevance are three retrospective studies that concluded that patients with gunshot wounds limited to the
head do not have cervical spine injuries
and do not require immobilization.95-97
Despite there being little evidence to support cervical spine immobilization for victims of blunt trauma solely on the basis of
injury above the clavicle, the majority of
studies still conclude that, "Immobilization of the patient with an injury above the
clavicle is prudent until a physician is able
to evaluate the patient fully for possible
cervical spine injury and determine the
need for radiographs."36
This recommendation is, no doubt, based
upon an assumption that the overall risk of
spine immobilization is so low that there
is no reason not to immobilize every patient in whom there is any question about
whether a cervical spine injury is present.
This may or may not be a reasonable assumption in a civilian setting, but as noted
later in the discussion about cervical spine
immobilization, it is probably not a reasonable assumption in a combat setting.
Clinical Findings in Cervical Spine
Injury
Fortunately subtle, occult, or delayed neurological injury is quite rare. In most patients with spinal cord injury, neurological
impairment is clinically apparent early in
the course of evaluation.98, 99 This certainly seems to be true in the case of penetrating neck injury, although delayed neurological damage has been described.44, 52,
99
Prehospital evaluation of penetrating neck
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trauma should include consideration of the
mechanism of injury, wound location, and
the presence of suspected entry and exit
wounds. Although it has been suggested
by some that the reliability of the prehospital clinical evaluation for the potential of
spine injury is not affected by the mechanism of injury (Domeier et al.),101 there is
no question that, in fact, the probability of
spine injury is affected by the mechanism
of injury and the amount of potential energy transfer. There are differences in
probability of spine injury between penetrating and blunt trauma. It is also certain
that a victim of a high-speed motor vehicle accident or a fall from a significant
height is much more likely to have a spine
injury than someone who has tripped and
fallen.
Undoubtedly the results of the civilian
Domeier study were influenced by the
inclusion of elderly patients who tend to
have degenerative bone disease and a
higher probability of malignant lesions
that would predispose them to injury from
even minimal forces. This is not an issue
for active duty soldiers, for whom a substantial amount of force is required to
cause an injury to the spine.
In terms of causing spine injury, penetrating wounds caused by knives and bayonets are different from those caused by
projectiles, and wounds caused by highvelocity bullets are different from those
caused by handgun bullets and fragments.100 Although the true path of a penetrating wound, even when there is an entrance and an exit, cannot be determined
by examination of the external wound(s)
none of these wounds should ever be
probed.
Knowledge of the size and type of blade
and the angle of entry (if it can be determined) is useful in estimating what struc-
18
Immediate Care of the Wounded
Clifford C. Cloonan, MD
tures might have been damaged by a stab
wound. The position of the casualty and
the trajectory of the wounding projectile
can also be used for the same purpose.99 In
most instances, stab wounds to the neck
cause fewer severe injuries than do projectiles. In a review of 218 patients with
penetrating neck injuries undergoing mandatory surgical exploration, stab wounds
had a 10% higher rate of negative exploration than injuries from projectiles.102 The
bottom line, however, is that a physical
examination of the patient and a good description of symptoms from the patient are
most important in making a diagnosis of
spine, and particularly neurological, injury.
Priaprism, or penile erection due to retention of blood, is a diagnostic finding in
spinal cord injury, especially cervical
spine injury. The following guidelines are
given for patient assessment in the field in
the 2004 edition of Intermediate Emergency Care: Principles & Practice:
Examine the male organ for priaprism, a painful, prolonged erection
usually caused by spinal cord injury
or blood disturbances. Suspect a major spinal cord injury in any patient
with a priaprism.103(p.524)
Despite considerable effort no studies
where found that addressed the incidence
of priapism in spinal cord injured patients
or that associated specific types of spine
injury with the development of priapism.
Although there is a paucity of data numerous texts and training manuals make reference to the need to check for the presence
of priapism as a marker for spinal cord
injury so it seems reasonable to make the
same recommendation here as well. The
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sensitivity and specificity of priapism as a
marker for spinal cord injury is unknown.
Patients may have either complete or partial spinal cord injury. A complete spinal
cord injury is defined as total loss of sensory or motor function below a certain
level. If any motor or sensory function
remains (e.g., sacral sparing), it is considered an incomplete injury. The prognosis
for recovery from an incomplete injury is
significantly better than from a complete
spinal cord injury. It is particularly important that patients with incomplete injury be
handled with care to prevent worsening of
their condition and that they be quickly
transferred to the care of neurosurgeon.
Signs of sacral sparing include the presence of perianal sensation, rectal sphincter
tone, and any ability to move the toes104
The sensory level of the cord injury is defined by the most caudal segment of the
spinal cord with normal sensory function
on both sides of the body. The motor level
is defined as the lowest key muscle innervation that maintains a 3/5 (able to move
against gravity) muscle grade.
Assessing deep tendon reflexes is also
helpful in assessing for the presence of a
spinal cord injury and this can certainly be
done near the point of wounding. In the
acute setting, muscle paralysis with intact
deep tendon reflexes typically indicates a
spinal cord (upper motor neuron) lesion,
whereas paralysis with absent deep tendon
reflexes suggests a nerve root or cauda
equina (lower motor neuron) lesion. Because lower motor neuron lesions are often surgically correctable, this distinction
is important. The deep tendon reflexes that
are important to assess are as follows:
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
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Location of Loss of Deep Tendon Reflexes
Biceps
Triceps with intact reflexes at biceps
Patellar and Achilles tendon with intact upper extremity reflexes
Achilles tendon only
Penetrating injury can cause isolated
lower motor neuron injury either at the
nerve root or more distal. Such an injury
produces a loss of motor function and sensation over a specific dermatomal area that
corresponds with the level of the involved
nerve root. Although nerve root damage
from penetrating injury can involve more
than one level, it can be differentiated
from spinal cord injury by the fact that
motor function and sensation below the
level of injury are preserved. This condition may be confused with BrownSéquard’s syndrome of spinal cord injury
(see below), which also involves unilateral
sensory and motor function loss, but it
only involves one or two levels of dermatomes and does not have a contralateral
loss of position and vibratory sensation.
Spinal shock (not to be confused with neurogenic shock) is characterized by flaccidity and loss of reflexes after a spinal cord
injury. Because spinal shock involves
complete loss of neurological function, it
can cause an incomplete spinal cord injury
to mimic a complete cord injury. Spinal
shock is a concussive injury to the spinal
cord that usually lasts less than 24 hours.
Return of the bulbocavernosus reflex may
signal the end of spinal cord shock.104
Neurogenic shock, which has already been
discussed at length in the chapter on Circulation, refers to the shock state caused
by loss of vasomotor tone and sympathetic
innervation of the heart. The loss of vasomotor tone leads to vasodilatation with
pooling of blood that produces hypoten-
Indicated Location of Lesion
At or above C6
C7
T1 – L4
L3 – S1
sion. Loss of sympathetic innervation of
the heart, if it is present, results in a lack
of the normal tachycardia seen in other
shock states.
Incomplete spinal cord injuries are associated with specific patterns of neurological
involvement. Approximately 90% of incomplete spinal cord injuries are classified
as one of three distinct clinical syndromes:
(1) Central cord syndrome,
(2) Anterior cord syndrome, and
(3) Brown-Séquard’s syndrome.104
The most common of these syndromes in
the general population is the central cord
syndrome.104 Because the central cord syndrome usually occurs in older patients
with degenerative arthritis who have sustained a hyperextension injury, it is not the
most common injury pattern found in military combatants (although it has occurred
in older military personnel). In the central
cord syndrome, the ligamentum flavum is
thought to buckle into the spinal cord, injuring the central gray matter and the most
central portions of the pyramidal and spinothalamic tracts.104 This damage produces weakness, possibly accompanied by
a variable degree of sensory loss, that is
disproportionately greater in the upper
than in the lower extremities. Central cord
syndrome can occur with or without cervical spine fracture or dislocation.
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
The anterior cord syndrome usually results
from a flexion mechanism that produces a
spinal cord contusion or is the result of a
protrusion of bony fragments or a herniated disk into the spinal canal. Injury,
thrombosis, or laceration of the anterior
spinal artery can also cause the anterior
cord syndrome. On physical examination,
this syndrome is characterized by bilateral
paralysis and hypalgesia below the level
of injury, with preservation of the posterior column functions of position and vibration sense. Anterior cord syndrome has
the poorest prognosis of the incomplete
injuries.
Brown-Séquard’s syndrome, or hemisection of the spinal cord, is a rare injury in
civilian settings. This syndrome usually
results from penetrating injuries, especially stab injuries, but it can also occur
following lateral mass fractures of the cervical spine.104 Brown-Séquard’s syndrome
consists of ipsilateral loss of motor function and vibratory and position sense (posterior column) associated with contralateral sensory loss beginning one to two
levels below the level of injury. As noted
in the experience of the Russians during
WWII, "Neurologic violations with the
puncture and cut wounds were frequently
expressed in the Brown-Sequard Syndrome."35 (p.21)
Spine Injury Treatment
Initial Management
The goal in the management of casualties
with potential spinal cord injuries at or
near the point of wounding is to prevent
new primary cord injury and to minimize
the effects of delayed secondary injury.
Delayed secondary cord injury results
from a cascade of autodestructive forces105
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and is particularly common following
blunt spine injury. Secondary cord injury
can occur hours or even days after the initial injury and is responsible for much of
the spinal cord damage that follows nonpenetrating injury.
Although prevention and treatment of spinal cord damage is very important, it does
the casualty no good if he or she dies with
an intact cord; so the initial management
of all such casualties must be on securing
the airway and stopping all controllable
blood loss. Management of the multiply
injured trauma patient with potential cervical spine injury should proceed in an
organized manner, following the ABCDE
approach to trauma care as recommended
by the American College of Surgeons'
Committee on Trauma in the Advanced
Trauma Life Support (ATLS) course
[American College of Surgeons, Committee On Trauma. ATLS - Advanced
Trauma Life Support Program for Doctors. 7th ed. Chicago, IL: American College of Surgeons; 2004]. Airway maintenance with cervical spine protection is the
first step in the ABCDEs of the primary
survey.
Concern about cervical spine injury
should not delay performance of the primary survey or resuscitation. Such resuscitation should be initiated as soon as the
need is identified, with due consideration
for the possibility of spine injury. This is
especially important when the mechanism
of injury is a fall from a height or a motor
vehicle crash.36
Airway Management
The prehospital care provider must identify the casualty whose airway is at risk.
Combat casualties with potential cervical
spine injury can have many reasons for
airway compromise. Maxillofacial inju-
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Clifford C. Cloonan, MD
ries, foreign bodies (e.g., teeth); blood and
secretions; cervical cord lesions; and associated head, neck, or chest injuries can all
place the combat casualty's airway at risk.
Initial airway management, which is often
all that is required, should include basic
maneuvers such as the chin-lift, jaw thrust,
placement of a nasal or oral airway, and
suctioning.36
As Chiles and Cooper note in their New
England Journal of Medicine review of
acute spinal cord injury, "The most immediate threat to patients with injury of the
cervical spinal cord is hypoxemia from
hypoventilation or aspiration of gastric
contents."106 Suderman et al. note that,
"…neurologic complications of intubation
are rare provided that the unstable cervical spine is immobilized during establishment of the airway.”107 And finally Apfelbaum et al. state that, "The primary concern in managing [patients with penetrating neck wounds] has been control of
bleeding and airway management.”44
Choosing the optimal airway management
technique is often perceived as a clinical
dilemma due to the belief that orotracheal
intubation is hazardous in the presence of
a cervical spine injury.108 According to
Rhee et al.109 and Einav,110 the most important considerations in deciding how to
provide a definitive airway in a potentially
cervical spine injured patient are operator
skill and comfort with the procedure.
These authors and others107, 111, 112 have
demonstrated that orotracheal intubation
with in-line immobilization is a safe and
effective method for definitive airway
management. Gerling et al., using a cadaver model, showed no significant vertebral body movement during orotracheal
intubation with manual in-line stabilization, although they did find that a significant amount of distraction occurred during
orotracheal intubation with cervical collar
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immobilization.113 In addition, the authors
report no significant difference in vertebral body movement when using different
laryngoscope blades.
ATLS guidelines recommend orotracheal
intubation with in-line manual cervical
spine immobilization as the initial definitive airway procedure in the apneic patient. In the breathing patient who requires
a definitive airway, the following sequence is recommended:
1. Perform nasotracheal or orotracheal intubation
2. Perform orotracheal intubation
with pharmacologic adjuncts if intubation is both required and impossible without such adjuncts
3. Avoid paralytic agents if at all
possible, because patients who
are paralyzed must be ventilated
or they will die
In trauma patients with potential cervical
spine injuries who require intubation (a
very rare circumstance in combat casualties), a surgical airway may have to be
established when intubation cannot be accomplished by other means.36
Individuals providing care at or near the
point of wounding should not delay transport to perform detailed clinical examinations or extensive stabilization. Patient
evaluation and management should follow, or at least be concurrent with, resuscitation.
Airway management of patients with
penetrating neck injuries is risky, even in
the best of circumstances, and the point of
wounding is not the best of circumstances.
Numerous potentially life-threatening
complications (e.g., severe hemorrhage
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Clifford C. Cloonan, MD
and inability to intubate secondary to distorted anatomy) can occur when advanced
airway management is attempted on casualties with penetrating neck wounds. For
this reason, it is recommended that intubation, or other advanced airway techniques,
be attempted only in casualties who are
(1) Anticipated to have a long transport time and have some sign of
airway obstruction such as stridor
suggesting severe respiratory
compromise and
(2) Apneic (note: an apneic and
pulseless combatant casualty with
a penetrating neck wound is dead
and no procedures are indicated).
If evacuation can be done expeditiously,
advanced airway management should be
delayed until a more skilled provider with
better equipment, support, and lighting is
available. In such circumstances advanced
airway procedures should be attempted
only in the case of impending or full respiratory or cardiac arrest.
If indicated, and if the care provider is
qualified, orotracheal intubation is the preferred route99 because the airway can be
visualized directly and there are fewer
associated complications. It is also the
technique that most care providers are
trained and experienced in performing. If
a casualty with a penetrating neck wound
must be intubated, it should be done without neuromuscular paralytic agents if at all
possible.
Cricothyrotomy may need to be performed
when orotracheal intubation is unsuccessful, or is impossible114-116 but it must be
considered the final airway option in patients with penetrating neck trauma because of the risk of life-threatening hemorrhage.
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Controversy exists about the performance
of cricothyrotomy by prehospital personnel.115, 117, 118 Mortality rates are high when
prehospital cricothyotomy is performed on
patients with penetrating neck trauma, but
it is unclear whether this is a function of
the experience (or lack thereof) of the
provider or the degree of injury sustained
by these patients If a surgical airway must
be established, perhaps a safer technique
would be percutaneous needle cricothyotomy, which requires little to no incision, and thus may reduce the risk of lifethreatening hemorrhage.119
No studies address the safety and efficacy
of this procedure when performed on
casualties with penetrating neck wounds.
Cricothyrotomy, with or without a needle,
is risky and difficult, particularly when an
anterior neck hematoma is present (presenting a high risk of catastrophic hemorrhage). Even bag-valve-mask ventilation
(BVM) may be hazardous when used on
patients with penetrating neck trauma. If
there is injury to the airway, the positive
pressure generated by BVM ventilation
may cause dissection of air into the surrounding tissues, resulting in death from
airway or vascular complications. BVM
ventilation should be regarded as a temporizing measure until a more definitive airway is achieved.99
Immobilization
In civilian settings, ambulances generally
carry the needed immobilization materials
to the patient, but in combat, immobilization materials are carried to the patient on
the back of the care provider. In the combat setting, therefore, a backboard is out of
the question; no combat medic would, or
should, carry a backboard into a combat
environment, although a field-expedient
backboard, such as a door, is a reasonable
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
option if available and clinically indicated.
Even a stretcher may be unavailable at or
near the point of wounding. Usually, the
only question for the combat medic is
whether or not to carry a cervical collar.
An evaluation of the efficacy of using a
cervical collar alone to stabilize cervical
spine injuries has yet to be done. If a patient cannot be secured to a backboard (or
at least a litter), it is unclear if there is any
added value from applying a cervical collar.
Spine Boards From United States Naval Hospital
Corpsman 3 & 2 Training Manual
NAVEDTRA 10669-C June 1989
The issue of spine immobilization at or
near the point of wounding is somewhat
contentious. That a small subset of casualties with blunt or penetrating neck trauma
could benefit from spine immobilization at
or near the point of wounding is indisputable. The issue is whether or not the civilian EMS model of immobilization for all
patients with a possible spine injury applies in combat. At or near the point of
wounding, immobilization is often impractical, if not impossible, and the poten-
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tial benefits do not necessarily outweigh
the risks/costs.
The Literature Supporting
Immobilization
As noted by Hoffman et al.,78 no attempt
will ever be made to prove the efficacy
and safety of prehospital spine immobilization with a randomized controlled trial
because it is, "unimaginable that emergency physicians would allow patients
with known cervical spine injury to remain
unrestrained." Ethics certainly preclude
"allowing patients with [cervical spine
injury] to bump around unprotected on an
ambulance just to prove that it is or is not
really dangerous,"78 but a study that
would help determine whether the benefit
of immobilizing all patients with potential
spine injury outweigh the risks would be
extremely useful. The underlying assumption is that the risk to patients from spine
immobilization is so small that it would be
unethical to conduct such a study. When
applied to a combat scenario, however this
assumption may not be correct, and only a
study that assesses not just neurological
outcomes but also overall morbidity and
mortality from all causes will be able to
answer this question.
The studies and other articles currently
available on this topic are more anecdotal
than rigorous, and when scrutinized carefully do not make the case with any degree
of certainty. Routine immobilization of all
patients with possible cervical spine injury
is based on literature that warns of spinal
cord injuries being sustained during the
prehospital phase of care. Rogers, in his
sentinel 1957 retrospective review of 77
patients with blunt cervical spine injuries,
stated that, “It is a sad commentary that in
one in every ten patients symptoms of cord
compression or an increase of cord symp-
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Clifford C. Cloonan, MD
toms developed subsequent to the time of
original injury - during emergency care,
during the time when the diagnosis was
being established, during definitive treatment, or following reduction.”120
This comment is often quoted as the reason for the prehospital cervical spine immobilization practice that has become the
standard of care. In fact, this article has
served as a major reason for the universal
practice of spine immobilization with rigid
cervical collar, sandbags or taped block,
and a long spine board.120 It is interesting
to note, however, that in Rogers’ review,
in all cases in which spinal cord damage
occurred during treatment, the cord injury
occurred either during surgical stabilization or following it, not as the result of
prehospital care. Rogers describes not a
single case in which spinal cord injury
occurred during transport from an accident
site or during treatment in an emergency
department, yet his article is often cited as
evidence of the risk of causing cervical
spine cord injury during prehospital
movement.120
Other articles, including those by Podolsky et al.,121 Cloward & Netter,122 and
Geisler et al.123 attribute delayed spinal
cord injuries to improper prehospital handling, but fail to provide supporting data
in their published reports. A 1977 review
and epidemiologic study by Riggins &
Kraus,50 reported a 39% incidence of neurologic deficit for all cervical spine injuries, but they did not attribute these injuries to "improper handling during transport." None of this should be interpreted
to suggest that spinal cord injury cannot
occur, or even has not occurred, as the
result of improper handling; it most certainly can and has. It is clear, however,
that no evidence supports the assertion
that this is, or ever was, a common occurrence.
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Further complicating the debate is the role
patients themselves play in minimizing
their injury. In the same way that trauma
patients instinctively hug their ribcage and
breathe more shallowly to minimize internal injuries, or hold an injured arm close
to the body for splinting, patients with
spine injury may often be capable of protecting themselves from spinal cord damage.124
In a retrospective study by Hauswald et
al., patients cared for in New Mexico,
where prehospital cervical spine immobilization is standard practice, were compared with patients cared for in Kuala
Lumpur, where prehospital cervical spine
immobilization is not the standard. Types
of injuries and patient ages were similar in
both groups. Despite near universal spine
immobilization in the United States, the
odds ratio for disability was actually
higher, after all independent variables
were corrected for, for U.S. patients than
for Malaysian patients (OR 2.03), corresponding “to a <2% chance that immobilization has any beneficial effect.”124 Although it is unlikely that immobilization
actually causes spinal cord injury, this
study at least serves to raise questions
about our current practice.
The current practice of near universal
spine immobilization for all trauma victims with suspected spine injury has
evolved despite a lack of systematic
analysis of the risks associated with immobilization or lack thereof. In civilian
practice, the potentially disastrous consequences associated with failing to properly
immobilize patients who have unstable
spine injuries are viewed as far outweighing any other consideration. At the point
of wounding in combat, however, immobilization has inherent risks that are not
typically seen in civilian EMS.
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
Risks Associated with Immobilization
at, or near, the Point of Wounding
From FM 21-10
As mentioned above, the realities of combat often preclude immobilization of casualties. Even when immobilization is possible under these circumstances, it may not
be recommended. Immobilized combat
casualties are often left unattended during
evacuation or when attendants must turn
their attention to protecting themselves
and their patients from enemy fire. This
places such casualties at risk for aspiration
or impaired ventilation. Cervical spine
immobilization may also conceal lifethreatening injuries such as an expanding
hematoma or blood loss.30
Aspiration is a risk in immobilized patients, particularly in those with some degree of altered mental status who are restrained in a supine position. Relatively
recent studies reiterate the risks of aspiration,125 and the need to have suctioning
equipment on hand..55 (p.364) If vomiting
does occur, patients should immediately
be placed on their sides, maintaining spine
alignment, while suctioning is performed.
In the case of immobilized patients who
are intoxicated, Kirk & Pace126 suggest
that the backboard not be attached to the
gurney so the patient can be turned on the
board to aid in airway clearance. In short,
immobilized patients must be constantly
observed by a provider with the necessary
skills and equipment needed to keep the
airway clear. Unfortunately, in a combat
setting, this is rarely possible so aspiration
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is a very real risk. Even in civilian settings, aspiration occasionally occurs as the
result of immobilization.
Immobilization on a backboard has also
been associated with impaired ventilation.127 It has been clearly demonstrated
that standard and appropriately applied
spine immobilization devices can significantly reduce pulmonary function and respiratory capacity, even in healthy individuals.128, 129 The supine position itself
has been noted to have a detrimental effect
on pulmonary function.130, 131 Bauer &
Kowalski note that, "…closer observation
of patient ventilatory function while affixed to these devices is indicated. The
common practice of leaving patients
strapped to these [spine] boards while in
the emergency center could hamper respiratory function."128
Unfortunately, at or near the point of
wounding and throughout evacuation to
definitive care, it is often not possible to
keep immobilized casualties under close
enough surveillance to ascertain whether
their respiratory function is impaired. Furthermore, combat casualties often have
multiple injuries, so it is not uncommon
for an individual to have both a potential
cervical spine injury and a lung injury
with compromised ventilation. In cases of
isolated cervical spine injury ventilation
will be impaired if there is cord injury
above C5.
Another way in which immobilization on
a long backboard can cause harm is by
creating pressure sores. This is not an insignificant problem, particularly for patients who have sensory loss as a result of
spinal cord injury. Pressure sores not only
add to the burden of injury, but are complex wounds that heal slowly.132 Cordell et
al.133 note that several studies have associated use of the spine backboard with both
26
Immediate Care of the Wounded
Clifford C. Cloonan, MD
patient discomfort and the development of
pressure ulcers.134-137 Casualties immobilized and evacuated in combat could spend
a considerable amount of time on a backboard, thus increasing their risk of pressure sores if they have spinal cord injury.
Even as few as 2 hours spent on a spine
board has been reported to cause pressure
ulcers.136
Finally, lying on a backboard can be quite
painful even if the patient has no injuries
at all133, 134, 137 It is quite possible that the
pain associated with immobilization may
become so severe that a patient with a
spine injury may move around in an effort
to get comfortable and might thus cause
neurological damage that might not otherwise have occurred. Cordell et al. suggest that through this mechanism, spine
boards could actually contribute to "antiimmobilization."133
In sum, the following guidelines should be
followed at or near the point of wounding:
•
Do not immobilize patients who
don’t need to be immobilized
•
Safely remove immobilized patients
from the backboard as soon as possible, especially if they have a
known spinal cord injury
•
If possible, lay an air mattress on
top of the spine board to reduce pain
and pressure that can lead to pressure sores133 (this may not be feasible in a combat situation)
•
Remove all hard objects, such as
knives and other weapons, from the
pockets of immobilized casualties,
particularly in those who are paralyzed. Failure to do so may cause
severe pressure sores.120
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Steroids for Known Spinal Cord
Injury
Steroids have long been used in hopes of
limiting the extent of secondary spinal
cord injury, despite the lack of supporting
scientific data. The use of steroids in the
treatment of neurotrauma was based upon
their theoretical ability to inhibit lipid peroxidation, stabilize lysosomal membranes,
and modify edema production.138 Based
upon the results of the Second National
Acute Spinal Cord Injury Study (NASCIS
2), the current civilian recommendation is
to treat patients with nonpenetrating spinal cord injury with high-dose methylprednisolone within the first 8 hours of
injury.139
This protocol was derived from a study
done by Bracken et al., who found that
patients treated within 8 hours of injury
with methylprednisolone, 30 mg/kg intravenous bolus given over 15 minutes, followed by a 45-minute pause then a 5.4
mg/kg/hr infusion for 23 hours, showed
significant neurological improvement at 6
weeks, 6 months, and 1 year when compared with patients treated with naloxone
or placebo.139, 140
But even this government recommendation has been recently challenged.141-143
Although it may be reasonable to apply
this recommendation to combat casualties
with nonpenetrating spinal cord injuries, it
is unclear whether, in total, such a recommendation would produce the best patient outcomes in this patient population,
in a combat setting; and there is no evidence to support the use of high dose steroids in casualties, civilian or military, who
have cord damage from penetrating injury.
A high-dose, short course of corticosteroid
appears to have no documented serious
side effects but, as noted in a recent re-
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Clifford C. Cloonan, MD
view of the effects of single-dose glucocorticoid administration, data are only
available from small-scale heterogenic
studies.144 No large-scale studies of standardized surgical procedures have been
done that could establish the safety of glucocorticoid administration in situations
that might have a higher risk of wound
and infectious complications (e.g. combat
casualties).
Evacuation
Few patients with penetrating injuries of
the spine need to be evacuated directly to
a facility with neurosurgical capabilities
because experience has borne out that
most such patients, particularly if the injury involves the cervical spine, have
other injuries that are more immediately
life threatening. Neurosurgical care is
rarely available within a 1-hour evacuation time, so patients needing urgent surgical intervention should be taken to the
closest facility with resuscitative surgical
capability. It is only appropriate to evacuate directly to a neurosurgeon when
(1) No associated life- or limbthreatening injury is present
(rarely possible to establish at or
near the point of wounding given
the absence of advanced diagnostic capability or prolonged observation) or
(2) There is a neurosurgeon at the
nearest resuscitative surgery facility.
During evacuation, immobilized casualties
must be attended by a care provider who is
capable of and properly equipped to maintain the airway. If the evacuation is anticipated to take longer than 1 hour, especially if the casualty is paralyzed, the risk
of pressure ulcers can be reduced by pad-
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ding the backboard and by shifting the
patient's weight periodically by tilting the
board from side to side.
Care of the Casualty with Head
Trauma
Initial Management
As in the management of patients with
spine injuries, initial management of patients with both blunt and penetrating head
trauma should focus on immediate life
threats, e.g. airway, breathing, and circulation. Absent any obvious exsanguinating
hemorrhage, the first concern should be
the airway.
Often casualties with penetrating head
injuries, and some with blunt head trauma,
have maxillofacial injuries that involve the
airway. Even when there is no direct damage to the upper airway, the airway of
head-injured casualties is at risk. Such
patients quite frequently have altered mental status and, particularly when in the supine position, they are at risk of airway
obstruction. Obstruction can occur from
prolapse of the tongue and/or aspiration of
vomit, blood and tissue. Wounds to the
head and face are common causes of airway obstruction in combat casualties. In
both civilian and military combat settings
head injury is the leading indication for
intubation in a trauma setting (see Airway
chapter, above).145, 146
The airway management recommendations for head and face injured casualties
such as those provided by Jolly during the
Spanish Civil War147(p.137) and by Beecher
and others during WWII148 (p.982) remain
valid today. Specifically, casualties with
serious head injuries should be transported
in the lateral recumbent or prone position
with the head turned to the side. If it is
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
necessary for any reason, such as cervical
spine immobilization, to transport such
casualties in a supine position, an attendant with ready access to suction and
skilled in airway management must be
present throughout the transport.
Early and adequate ventilation and oxygenation are particularly critical for headinjured casualties. With gunshot injuries to
the head, fatal apnea often occurs immediately after injury as energy is transferred
from the bullet to the brain. Available evidence suggests that intracranial shock
waves caused by high-velocity bullets can
cause brain-stem compression and thus
interfere with the cardiorespiratory function of the medulla oblongata.21, 28, 29, 149-151
It is therefore likely that, even under ideal
circumstances in which a casualty with
penetrating brain injury is immediately
attended to and rapidly evacuated, survival
is unlikely, even if the initial injury was
not otherwise lethal.152, 153 The evidence
from Korean War casualties certainly suggests that this is the case.16 (p.44)
It is essential that all controllable hemorrhage be controlled. The critical influence
of cerebral perfusion pressure on outcome
in brain-injured patients is discussed in
detail below. A difficult balancing act
must be carried out when treating multiply
injured combat casualties with head injury
and internal bleeding. Although uncontrolled internal hemorrhage is increased
when intravenous fluids are administered,
which is why aggressive fluid resuscitation is not recommended in most such circumstances, more aggressive fluid resuscitation may be necessary when serious
head injury is present. As discussed later
in detail, it is important to maintain cerebral perfusion pressure even at the risk of
increased internal bleeding. Even bleeding
from scalp wounds should be aggressively
controlled because blood loss from these
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injuries can be significant over time. Scalp
injury is present in a significant percentage of head-injured casualties.17
Blunt Head Trauma
Although the preceding discussion of the
epidemiology of head injuries in combat
casualties focused almost entirely on those
with injuries involving scalp lacerations or
intracranial penetration, an increasing percentage of combat casualties are sustaining blunt closed-head trauma. It was noted
during World War II that
"Emphasis, rather naturally was upon
penetrating head wounds as compared
with closed head injuries. It soon became evident, however, that in a
mechanized army, closed injuries and
the factor of blast could not be casually dismissed as potential causes of
cerebral trauma."154(p.91)
This statement is even more relevant today. As the number of penetrating injuries
has decreased in American troops during
combat, the frequency of blunt injuries has
increased. Increased insertion of troops by
parachute, fast roping, and helicopter or
other aircraft, and more urban combat all
contribute to an increased risk of closed
head injury.
Closed-head injury ranges from minor
concussion, with transient or no loss of
consciousness (LOC), to severe intracranial injury, and death. The challenge today
is for military prehospital care providers to
rapidly and effectively triage and treat all
patients within this spectrum. Any blunt
head injury that produces LOC, no matter
how minor or brief, produces some degree
of cerebral pathology (as imaging technology improves, more of this pathology
is being identified). The great majority of
such patients suffer either minor, or no
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
demonstrable, long-term consequences.
Those with persistent symptoms probably
have sustained a cerebral contusion from a
contracoup mechanism.
In patients at both ends of the spectrum of
severity of injury, evacuation for the purpose of rapid treatment is typically not
indicated. Evacuation of patients with minor head injury generally has no effect on
their outcome, which is almost always
good.
At the far end of the spectrum of blunt
brain injury with no associated intracranial
bleeding is diffuse axonal injury (DAI),
which may range from mild to severe.
DAI is present to some degree in many
patients with severe head trauma, and is
almost always the result of an injury in
which rotational acceleration has created
high shear forces on the brain parenchyma. Patients with DAI are generally
those who were rendered unconscious at
the moment of sudden injury and in whom
the pathological changes induced by these
shear forces are not identifiable as a mass
lesion on head CT.155
The duration of DAI-associated LOC may
range from 6 to 24 hours in its mildest
form (15% associated mortality) to a permanent comatose/vegetative state (or
death) in severe DAI (>25% mortality
with a poor prognosis in virtually all
cases).156 Despite, or perhaps because of,
the poor outcomes associated with DAI,
patients with DAI typically benefit little
from early evacuation to a neurosurgeon.
Patients who benefit most from accurate,
far-forward diagnosis and appropriate
treatment are those with focal intracranial
bleeding, especially those with epidural
bleeding, Epidural bleeding usually occurs
in association with a temporal bone fracture and is caused by rupture of the middle
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meningeal artery. This can occur even
when there has been relatively little energy transfer to the brain. Because epidural hematomas are caused by arterial
bleeding, they expand rapidly and cause
death if not treated quickly. Conversely, if
quickly diagnosed and treated, such patients typically do well because the brain
itself usually sustains no serious damage.
Other forms of intracranial bleeding are
cerebral, subdural, subarachnoid, intracerebral, and intraventricular bleeding.
Unlike epidural hematoma, these other
forms of bleeding usually indicate that the
brain has been subjected to a high energy
force. Even with appropriate initial treatment and rapid evacuation to skilled neurosurgical care, patients with such injuries
often do poorly. In the general civilian
population, patients with epidural hematomas make up only about 0.5% of all patients with closed head injury and about
1% of those presenting in coma.156(p.308) It
can be calculated that approximately 10%
of this same group sustain subdural hematomas.156, 157
The much higher percentage of elderly,
alcoholic, and chronically ill patients in
the civilian population, as compared to the
military combatant population, increases
the relative percentage of patients with
subdural and other types of intracranial
bleeding. Thus the probability that a combatant with blunt head trauma and intracranial hemorrhage will develop an epidural hematoma is higher as compared to the
general civilian population. For this reason, in a military population, the percentage of patients with epidural hematoma
would be expected to be several times
higher than that seen in civilian series; but
still quite rare nonetheless.
It should be clear from the preceding that
the primary focus of military prehospital
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Clifford C. Cloonan, MD
personnel caring for combat casualties
with blunt head trauma must be on
(1) Immediate resuscitation, and then
(2) Early identification and evacuation
of patients who have neurosurgically correctable lesions, especially
those with epidural hematoma.
Prevention
Despite considerable advances in the diagnosis and treatment of patients with
neurological injury, after such injury has
occurred, there is often little beyond palliative care that can be provided. The central nervous system, once damaged, heals
very slowly, if at all. Therefore, the focus
of medical efforts in the realm of central
nervous system injuries must be on prevention.
Kevlar Helmet
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During World War II, a significant number of deaths resulted from motorcycle
accidents. A sizeable percentage of these
deaths were either solely, or in part,
caused by head trauma. As the result of a
recommendation to the British Army
Medical Research Council in 1941 by Sir
Hugh Cairns, the use of crash helmets by
British Army motorcyclists was made
compulsory. A study published in 1943 by
Cairns & Holbourn documented a dramatic decrease in motorcycle fatalities
following the implementation of this recommendation.158 A similar aggressive
head-injury prevention policy needs to be
followed today in all areas where head
trauma is reasonably likely.
Considerable advances have been made
since World War II in head-injury prevention, but there is still far to go. The Kevlar
helmet represents a significant improvement over the steel helmet in preventing
penetrating injury from fragments and
other low-velocity projectiles. The former
can even defeat some high-velocity projectiles in some circumstances. In general,
however, high-velocity assault rifle bullets
will penetrate the standard Kevlar helmet
and, contrary to popular belief, when
penetration does occur, the velocity of the
bullet is only minimally reduced as it
moves through the helmet. When a bullet
penetrates a Kevlar helmet, the resultant
head injury may be as bad, or even worse,
than if a helmet had not been worn at all
because the bullet retains most of its energy as it penetrates but the full metal
jacket may be deformed. Despite this fact,
because the primary risk in most battlefield situations remains fragments helmets
should always be used on the battlefield.
Overall Kevlar helmets are quite efficient
at reducing the risk of penetrating injury,
particularly lower velocity injury, but they
31
Immediate Care of the Wounded
Clifford C. Cloonan, MD
are much less effective against blunt injury. Unlike a motorcycle helmet that reduces intracranial injury by deforming
when force is applied, thus dissipating
energy, the Kevlar helmet is quite rigid
(which allows it to defeat penetrating
trauma) so it does a poor job at reducing
the transfer of blunt energy.
In the past some special operations troops
used a crushable, bicycle-type, helmet,
rather than the standard Kevlar helmet, for
some close combat situations because the
greatest risk for head trauma was felt to be
from blunt trauma and high velocity bullets, which Kevlar does not usually defeat.
The combat deaths of some of these elite
SOF troops from penetrating head wounds
while wearing these bicycle-type helmets
led to a change to a ballistic helmet. What
is clearly needed, especially for troops
with an increased risk of closed-head injury, e.g. airborne and special operations
troops, is a helmet that combines both ballistic protection and protection from blunt
force injury. Such helmets are already
used by aviators who also face the dual
threat of penetrating and blunt head
trauma. Airborne troops use soft foam inserts inside the Kevlar helmet to reduce
the risk of closed head injury during airborne operations; although these certainly
help, a better helmet would further reduce
the risk.
No improvements in helmet technology,
however, will address the main problem,
which is compliance. Troops frequently
cite a long litany of reasons why they don't
wear the helmet they are provided. These
include heat load, weight, perceptions of
decreased situational awareness due to
decreased ability to hear, and a desire to
blend in with the local population and to
appear less "threatening." Measures taken
to address these concerns would also help
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reduce the problem of CHI in combat
troops.
Diagnosis
Maj. Douglas Jolly’s 1938 notes from the
Spanish Civil War regarding the difficulty
of accurate and far-forward diagnosis in
head trauma are still true today. He stated
that
The subdivision of head wounds into
two clear-cut groups - those in which
operation can, and those in which it
cannot, be recommended - is unattainable even by those with an extensive experience in war surgery…All
that the discriminating surgeon should
allow himself to say of the most severe
head injuries is that they do not merit
priority treatment; but they should unfailingly be reviewed when there is
some respite from the rush of casualties.147(p. 84)
Those who provide care at or near the
point of wounding must determine which
head-injured patients must be rapidly
evacuated and which do not need to be
evacuated. As a general rule, all patients
with a head injury, except those with unequivocally minor scalp injuries, should
be regarded as having a potentially lifethreatening injury, and none, except those
having an injury that is obviously incompatible with life, should be treated as if
they were unsalvageable.
Head injury in itself is not always an indication for evacuation, but today it is impossible to definitively rule out serious
head injury at or near the point of wounding. While this might be interpreted to
mean that every patient with any head injury should be evacuated the contingencies of the battlefield would certainly not
allow this. What must happen is that easy
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Clifford C. Cloonan, MD
to use, durable, and light weight diagnostic tools must be developed and fielded for
far forward use as soon as possible. Absent this the forward care provider must
use common sense, knowledge of the epidemiology of serious head injury, and the
basic assessment tools of history and
physical examination to make these difficult triage decisions.
Most of Jolly's observations about the
management of casualties with head
wounds during the Spanish Civil War remain relevant today. He noted that, “Attempts at prognosis based on the course of
the projectile through the cranium are
liable to serious error….147(p. 85)” and that,
“…no scalp wound is so trivial that it
should not be regarded as potentially serious.”147(p. 84) His admonishment that,
"Blind groping for foreign bodies with
forceps can hardly be condemned too
strongly"147 (p. 97) should be strictly observed in all wound cases, but especially
in the case of penetrating head wounds.
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dural or epidural hematoma caused by
blunt trauma. For this reason, the primary
focus of the following discussion will be
on the assessment and disposition of the
casualty with the closed head injury.
When it is unclear whether a penetrating
head wound is present, experienced military neurosurgeons agree that obtaining an
immediate definitive diagnosis is unnecessary because such patients are not likely to
deteriorate en route.
When confronted with a casualty with
blunt head trauma at or near the point of
wounding, the key question is, "Must the
casualty be evacuated, and, if so, how urgently?" In the patient with a serious head
injury, particularly one with blunt head
injury, making the correct decision is essential. It has been shown that patients
with blunt head trauma who require and
receive surgery within 4 hours of their
injury have a mortality rate that is three
times lower than those who need surgery
but do not receive it for more than 4 hours
after their injury.159
During combat operations in Mogadishu
Somalia on 3 October 1993 a combatant
with a small, lightly bleeding head wound
of unclear cause presented to a casualty
collection point and was quickly neurologically assessed by a physician. He was
found to be neurologically intact, asked to
be returned to combat, and was allowed to
do so. A few days after the battle this individual returned again for medical
evaluation complaining of a headache and
clear fluid draining from the wound. A
radiograph of the head was obtained that
revealed a small fragment approximately 6
cm inside the brain. The casualty was
started on antibiotics and was evacuated.
During evacuation the patient seized and
developed a brain abscess, but eventually
recovered with good neurological function
(personal communication with Dr. Rob
Marsh, Special Operations Surgeon). This
case demonstrates that although early
evacuation is optimal, and certainly all
patients with a known or reasonably suspected penetrating head injury should be
evacuated to competent neurosurgical
care, such patients will often do well even
if there is a delay.
For the patient with penetrating head injury, the evacuation decision is generally
both less difficult to make and less critical.
It is usually easier to determine that a
casualty has sustained a penetrating head
injury than it is to diagnose an early sub-
Because minor blunt head trauma, with
and without transient LOC, is fairly common in military populations in both peacetime training and in war, it would be extremely useful to be able to quickly sort
out those who need the prompt services of
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Clifford C. Cloonan, MD
a neurosurgeon from those who do not. As
the U.S. military becomes increasingly
smaller and more specialized, overevacuation (evacuating casualties who do
not need to be evacuated) must be limited.
There is no piece of equipment and no
exam that far forward medical personnel
can use to quickly and accurately make
good triage and evacuation decisions for
head-injured casualties. There are, however, some things that can improve decision making in such circumstances.
Demographically most combatants are
quite similar to high school and college
athletes, so it is reasonable and appropriate to examine how athletes with closedhead injuries are evaluated on the field of
play to guide a similar evaluation of casualties with closed head injury at or near
the point of injury.160 Although serious
head injury is rare in organized athletics, it
does occur, and minor head injury is quite
common, particularly in contact sports
such as football. In the United States,
there are, on average, eight deaths each
year as a result of football-related head
injury, most which are caused by an acute
subdural hematoma.161 (p913),162
More than 200,000 minor head injuries
occur during organized football each
year,163, 164 and 70% of American football
players who are “knocked out” return to
play the same day.161 (p913) Returning to
combat is also what most likely happens
to the average combat casualty who suffers a brief loss of consciousness from a
closed head injury. Unfortunately, as in
athletics, a combatant who is rendered
unconscious may have only a mild concussion and can safely return to the field,
or he may have a developing intracranial
hematoma or other intracranial process
that may result in death or permanent neurological injury.165 The question of
whether it is possible to effectively and
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efficiently differentiate between these two
types of injury at or near the point of
wounding is the focus of the following
discussion.
Although there appears to be no difference
in severity of head injuries between
groups based on sex or race, it does appear
that age may be a factor. Jennett noted that
victims over the age of 60 are four times
more likely to have an intracranial abnormality on CT than their 166 Mostly this
information is useful because it indicates
that the risk of serious head injury for a
given degree of trauma is lower in population of military combatants than would be
the case in a civilian population that includes elderly patients. Most intracranial
injuries result from unprotected trauma
involving large forces. In the civilian setting, pedestrians and bicyclists struck by
automobiles have the highest potential for
serious intracranial injury.167 This only
suggests the obvious, i.e. that those sustaining higher energy blunt head injury
have the highest probability of serious
intracranial injury.
Information about mechanism of injury is
useful at or near the point of wounding to
risk-stratify head-injured combat casualties. It is possible to ascertain that patients
with high energy mechanisms of injury
will be at higher risk of serious intracranial injury, but it is not possible to achieve
a high degree of sensitivity or specificity
with this information. Some casualties
sustaining high-force impacts to the head,
for example, will have minor or no injury
and some who have sustained apparently
low-force impacts will later be found to
have serious intracranial injury.166, 167
Knowing whether a casualty with blunt
head trauma has had loss of consciousness
(LOC) is one of the most valuable pieces
of information in helping to make triage,
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
management, and evacuation decisions for
head-injured patients. It is commonly
thought that casualties with blunt head
injury but no LOC have a very low probability of serious intracranial injury and
probably do not need to be evacuated. As
pointed out by Cheung & Kharasch, however, this has not been proven; no study
has specifically analyzed the negative predictive value of LOC.167 In an evaluation
of patients with a GCS of 15 and LOC, the
incidence of identifiable intracranial pathology ranged from 6.1% to 9.4%.167
Most studies of the incidence of intracranial injury in patients with LOC do not
address the duration of LOC as a variable.
When this variable is considered, increasing duration of LOC is associated with
increasing incidence of intracranial lesions.169 Miller et al. noted an increase in
intracranial injury on CT from 5.9% in
patients with LOC < 5 minutes to 8.5% in
those with LOC >5 minutes,170 confirming
the earlier findings of Rivara et al. in a
pediatric population.171
Many if not most intracranial lesions identified on a CT scan following blunt injury
do not require surgery and cannot be significantly improved with any form of
medical intervention. The number of casualties who would benefit from rapid
evacuation to a neurosurgeon following a
closed head injury, then, is quite low, and
it is identification of this small group of
casualties that presents the challenge for
point-of-wounding care providers.
The available data appear to support the
widely held belief that the longer the
LOC, the higher the likelihood of serious
intracranial pathology and the greater the
need for rapid evacuation of the casualty
to the care of a neurosurgeon. It is important to note that the above discussion only
relates to the evaluation of casualties with
blunt head injury (a significant minority of
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combat-related head injuries) and should
not be applied to casualties with penetrating head wounds. Unless intracranial
penetration can be ruled out all patients
who may have sustained a penetrating
head wound need to be evacuated to a facility that can rule out intracranial pathology.
It would be useful if the presence or absence of such symptoms as headache and
nausea and vomiting could be effectively
used to raise or lower the clinical suspicion of an intracranial abnormality. Although the presence of these symptoms
often influences emergency department
decisions such as whether to obtain a CT
scan, such findings are neither sensitive
nor specific enough to predict intracranial
abnormality. The presence of headache,
and nausea and vomiting has not been
shown to be associated with an increased
risk of
(1) A surgically correctable intracranial
lesion,
(2) New-onset, post-traumatic seizures,
or
(3) CT-demonstrable intracranial pathology.166
In terms of physical examination, the
Glascow Coma Scale (GCS) is the most
widely used system for grading the neurological status of trauma victims. The GCS
is relatively easy to calculate and has been
shown, in civilian trauma settings, to be
reproducible with low inter-observer variability. When calculated by prehospital
care providers in the heat of combat, however, the inter-observer variability of the
GCS, however, is likely to increase dramatically, making the test much less reliable in this setting. Even with low interobserver variability, the GCS is not much
help in answering the most important
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
question, "Does this patient need to be
evacuated?"
Another problem with the GCS is that
most studies that have evaluated its predictive value have not addressed the important question of timing. A GCS obtained in an unconscious patient immediately after injury certainly has a different
predictive value than a GCS obtained in
the same patient an hour later.172, 173 It
would be very helpful if it were possible
to simply say that any casualty with a
closed head injury who has a GCS of 15
does not need to be evacuated and can be
safely returned to duty – unfortunately it is
not.
Unfortunately, even a perfect GCS of 15
does not exclude significant intracranial
abnormalities. The incidence, in the published literature, of CT-demonstrable intracranial injury in patients with a GCS of
15 varies between 2.5% and 22.5%.166
The high of 22.5% originates from the
neurosurgical literature and thus suffers
considerably from selection bias, i.e., only
those with a significant problem are referred to a neurosurgeon so patients with a
GCS of 15 and no intracranial pathology
never get into the neurosurgery database.
If only emergency medicine studies are
considered, a much lower incidence of
2.5% to 9.8% is found.166 The relevance of
this information to combat casualty management is hard to ascertain because surgically correctable lesions were not differentiated from other CT abnormalities: reported lesions varied from surgical epidural hematomas (urgent neurosurgery required) to simple linear skull fractures (no
surgery needed).
In the largest study assessing the frequency of CT abnormality in head trauma
patients with a GCS of 15, Shackford
found that 14.8% of 2,166 such patients
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had an abnormal CT but only 3.2% required a craniotomy.159 Miller et al., in the
largest emergency medicine series of
head-trauma patients with a GCS of 15,
reported that 6.1% of 1382 patients had an
abnormal CT but only 3 (0.2%) required
surgical intervention; all three having obvious depressed skull fractures.170 In another study of emergency department head
trauma patients with a GCS of 15, Jeret et
al. found a 9.4% incidence of CT abnormality but only 0.3% (2 of 712) required
surgery, one of whom died.174 It would
therefore seem that the percentage of head
trauma patients presenting to an ED or
battalion aid station with a GCS of 15 but
still requiring neurosurgical intervention is
very low -- but not zero. Although a GCS
of 15 does not exclude a CT-demonstrable
lesion (overall negative predictive value of
90.7%), there is clearly an increased risk
of serious brain injury with lower GCS
scores.
In every study to date there has been an
inverse relationship between GCS score
and frequency of CT-demonstrable intracranial abnormalities. This information is
of little use in making evacuation decisions for head-injured patients because all
patients with a low GCS score are generally evacuated as soon as possible in any
case and the GCS is not useful in deciding
what to do with the much larger number of
surviving head injury casualties who have
a GCS of 15.166
Physical Findings
Attempts have been made to establish a
relationship between anisocoria, external
signs of trauma, and neurologic findings
and the presence of significant intracranial
abnormalities.175 But, as Cheung &
Kharasch point out, few studies have
looked at these types of exam findings as
independent variables, so it is difficult to
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
arrive at a definitive conclusion regarding
such a relationship.167
Between 30% and 80% percent of head
injury patients with anisocoria have been
found to have demonstrable intracranial
injury, 167, 171, 175 and the incidence of intracranial abnormalities has been found to
increase with the degree of anisocoria.175
In a study by Borczuk of 210 head trauma
patients with anisocoria greater than 1
mm, only about one-third had an intracranial abnormality,169, 176 so although there
appears to be a reasonably high probability that a head trauma patient with anisocoria will have an intracranial abnormality, a sizeable number of head trauma victims with this finding will not. Signs suggesting basilar skull fracture such as "raccoon" eyes and hemotympanum have been
associated with a 53%-90% incidence of
intracranial pathology.171, 176
Even if a casualty with blunt head injury
and history of LOC has regained full consciousness and does not have a neurosurgically correctable lesion, a cerebral concussion has nonetheless been sustained
that is likely to produce some degree of
confusion and amnesia. Casualties with
such injuries may exhibit easy distractibility, poor vigilance, inability to maintain a
coherent stream of thought, inability to
carry out a sequence of goal-directed actions, delayed verbal responses or slowed
actions, disorientation, slurred or incomprehensible speech, problems with motor
coordination, emotional lability, and/or
short-term memory deficits. This confusion and memory disturbance can be immediate or delayed, so returning such
casualties to important duty positions is
problematic.177
The classic clinical picture of a patient
with an epidural hematoma is transient
LOC at the time of the injury, followed by
Disability
a normal level of consciousness (lucid
interval) over a variable period. This is
followed by a decline in mental status,
with a unilaterally (usually ipsilateral to
clot) dilated pupil, decerebrate posturing,
contralateral weakness, and often, unless
treated quickly, death. Although this sequence is considered characteristic of epidural hematoma, only about a third of patients with an epidural hematoma present
in this manner .178
Acute subdural hematomas occur approximately three times more frequently
in athletes than epidural hematomas.177 A
similar relative frequency of these conditions would be expected in combat troops
because they are demographically a similar population although exposure of combat troops to potentially much higher
forces may affect the relative frequency of
these conditions. In the general population
that has sustained head trauma, subdural
hematoma occurs almost twenty times
more commonly than epidural hematoma.156(p.308)
The reason for this difference between
athletes (and presumably combatants) and
the general population is because the general population includes young children
and the elderly both of whom have a relatively lower rate of occurrence of epidural
hematoma. This has been attributed to
there being a closer adherence of the dura
to the skull in these two groups and due to
skull elasticity in young children.156(p.308)
Furthermore, because of brain atrophy,
subdural hematomas are also much more
common in the elderly than in young adult
combatants and athletes. Because there is
less subdural space within which blood
can collect in young adults, in them when
subdural hematoma does occur there is
generally less pooling of blood in the subdural space and there is a higher degree of
underlying brain injury. For this reason
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
the symptoms associated with acute subdural hematoma in younger adults are
more often related to the underlying brain
injury rather than to the mass effect of a
clot so in this group an operation is less
likely to be beneficial.178
The combatant with an acute subdural
hematoma usually has prolonged unconsciousness and a focal neurological finding, such as pupillary asymmetry or decerebrate posturing so the evacuation decision is not difficult. Such casualties
should be evacuated to a neurosurgeon as
quickly as possible.
The above information is important because it makes it clear that in combatants
who have sustained serious head injury
epidural hematoma is relatively much
more common than would be the case in
the general population; this has disposition
and management implications. Compared
to a civilian population, combat casualties
with serious head injury are much more
likely to benefit from rapid evacuation to a
neurosurgeon.
One condition that has been well described in athletes engaged in contact
sports is a syndrome of massive cerebral
edema and death that follows relatively
minor head trauma occurring shortly after
a previously similar “minor” head injury.179, 180 This rare condition typically
presents in an athlete who, while still
symptomatic from a previous “minor”
head injury, returns to play before completely clearing his sensorium and then
suffers a second head injury. This syndrome, believed to be caused by persisting
cerebral vascular sensitivity, is called the
“second impact syndrome.” A second
injury then leads to cerebral autoregulatory dysfunction, vascular congestion, and
subsequent intracranial hypertension. This
condition, which can follow minor head
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injury without loss of consciousness, has
resulted in sudden death.181
Unfortunately there is no evidence to support the notion that a normal neurological
examination can accurately identify those
head injured patients who have minimal
risk of serious intracranial injury.166, 181, 182
Despite there being no good evidence to
support a point-of-wounding policy of
returning to duty most soldiers with blunt
head trauma, a GCS of 15, and a normal
neurological examination, such a policy is
probably still reasonable in the absence of
better far-forward diagnostic capability.
It is important to note, however, that, as
Cheung and Kharasch have pointed out,167
most studies simply do not address the
question of whether such emergency department patients can safely be sent home.
They focus instead on predictive factors
such as GCS < 15, focal neurologic deficits, and skull fractures. This is of little
use to the care provider at or near the
point of wounding, who will feel compelled to evacuate any head-injured casualty to someone who can rule out intracranial injury. In such a circumstance, the
evacuation decision will be made primarily upon the tactical situation and the
availability of transport. If both preclude
rapid evacuation and if, after some period
of observation, the patient appears to remain well, the care provider will likely
return him or her to duty. On the other
hand, if evacuation is available and the
tactical situation permits, the care provider
will likely evacuate the casualty.
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Clifford C. Cloonan, MD
Disability
Treatment
In the initial resuscitation of a combat
casualty with a potentially serious head
injury, the emphases should be on
(1) Ensuring an adequate airway and
adequate ventilation, and
(2) Controling hemorrhage.
Although the scalp can bleed significantly,
and can contribute to the development of
shock, scalp wounds in adults are rarely
the sole cause of hemorrhagic shock. It is
also true that serious brain injury can produce significant hypotension without concomitant loss of intravascular volume.
Despite these facts, any patient with a serious head injury who is also in shock
should be assumed to have another source
of bleeding (usually internal) until proven
otherwise. It should also be assumed that
altered mental status in a combat casualty
is due to head injury and is not due to
blood loss until proven otherwise.
Except in the case of severe shock, altered
mental status (aside from anxiety) is rarely
present in previously healthy young combatants without head injury or hypoxia. In
discussing the management of head injured combat casualties, during the Spanish Civil War, Jolly makes the still very
relevant observation that, "Time spent in
the systematic prevention and control of
bleeding is not lost."147(p89) It is absolutely
critical to the casualty with a serious head
injury to maintain adequate blood pressure, hematocrit, and oxygenation and
ventilation.183 All controllable bleeding
should be stopped; the airway kept patent;
and, if available, supplemental oxygen
should be provided (although achieving a
supranormal oxygen level provides no
benefit). The mean arterial pressure must
be kept greater than 70 mm Hg to ensure
adequate cerebral perfusion pressure.
In managing the head-injured casualty at
or near the point of wounding, the objectives must be to determine who needs urgent evacuation to the care of a neurosurgeon and who can be safely returned to
duty. Until there is an effective way, in
far-forward situations, to sort out which
casualties have sustained serious intracranial injury, there should be a low threshold
for rapidly evacuating such casualties
when circumstances permit.
Recently developed guidelines have been
published185, 186 to minimize the use of
head CT for patients with minor head
trauma. These guidelines could be used to
help make appropriate forward area triage
and evacuation decisions at or near the
point of wounding, but they have not been
evaluated for their effectiveness at reducing CT use even in a civilian population.
Several of the criteria are not generally
relevant to military combatants, such as
“age over 60” and drug or alcohol intoxication. Most of the others are so common
following head injury that they are not
likely to be very effective at reducing head
CT use and would result in substantial
over-evacuation if used solely to make
evacuation decisions in head injured combatants. These include
(1) Headache,
(2) Vomiting,
(3) Deficits in short-term memory
and,
(4) Physical evidence of trauma
above the clavicles.
The remaining criteria of seizure following head trauma would likely result in
evacuation even without implementation
of a published guideline. This despite the
fact that there is no proven correlation
between the presence or absence of new-
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Clifford C. Cloonan, MD
onset, post-traumatic, seizures and CTdemonstrable intracranial pathology.167
The Canadian CT Head rule has more
stringent criteria than those described
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above and may be more useful in making
evacuation decisions and reducing overevacuation.187
Canadian Head CT Rule: Selected Criteria
GCS score < 15 at 2 hours after injury
Suspected open or depressed skull fracture
Any sign of basal skull fracture (hemotympanum, ‘raccoon’ eyes, cerebrospinal fluid otorrhea,
Battle’s sign)
More than two episodes of vomiting
Retrograde amnesia > 30 minutes
Significant mechanism of injury (pedestrian struck by motor vehicle, occupant ejected from motor
vehicle, fall from height > 3 feet or five stairs)
Age > 65 years186 [Stiell, I. G., G. A. Wells, et al. (2001). "The Canadian CT Head Rule for patients with minor head injury." Lancet 357(9266): 1391-6]
I
n combat, dealing with the issue of the
second-impact syndrome is problematic because there is simply no way to
minimize the risk of recurrent head injury
in most combatants who are returned to
duty. When circumstances permit, casualties sustaining minor head injury should
be observed for a period of time and only
returned to duty when they are absolutely
symptom-free, or when their duties make
recurrent head injury very unlikely.
Although the circumstances of combat
will always be a major consideration in
the evaluation, management, and disposition of head-injured casualties the following approach, derived from recommendations for on-the-field management of
head-injured athletes should be followed
whenever possible:
•
celeration-deceleration-type force to
the head should be considered to have
sustained potentially serious head injury and should be thoroughly evaluated for level of consciousness,
steadiness of gait, orientation, posttraumatic amnesia, and retrograde
amnesia.
•
Casualties who have sustained only a
grade 1 concussion (no LOC or posttraumatic amnesia of < 1 hour duration) should be observed for 20–30
minutes. If there is complete clearing
of the sensorium and no residual
symptoms, such casualties can reasonably be returned to duty.
•
Circumstances permitting, casualties
with persisting symptoms, such as
headache, dizziness, or confusion,
should be evacuated for evaluation by
a physician.188
Any combatant who has received a
blow to the head or any significant ac-
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Clifford C. Cloonan, MD
•
All casualties with a grade 2 concussion (< 5 minutes loss of consciousness, amnesia < 24 hours) should be
evacuated for evaluation by a physician.
•
Casualties sustaining a grade 3 concussion, where there is prolonged or
severe alteration in level of consciousness or orientation, or a focal
neurological deficit should be evacuated, when possible, directly to a facility capable of performing a CTdirected craniotomy.
Because of the “second-impact syndrome,” casualties with minor head injury
present a dilemma because most in this
category do fine if returned to duty but a
very small number who sustain a second
minor head injury shortly following the
first may die. For this reason, when possible, no combatant who has sustained a
mild concussion should be returned to duties that have a relatively high risk of recurrent head injury for at least 1 to 2
weeks.181 Symptoms such as persistent
headache, irritability, fatigue, dizziness,
double vision, impairments in memory
and concentration, and/or problems with
behavior should lead to neurological or
neurosurgical evaluation.177 Repeated
"minor" head injuries have an additive
effect on cognitive abilities, 164, 189-193 so
any combatant with recurrent head injury
should be neurologically evaluated.
Steroids do not appear to offer any benefit
in the management of acute head injury.194
Because free radicals are thought to play a
major role in producing secondary injury,
free radical scavengers have been evaluated for possible use in the treatment of
head injured patients. Although there have
been some promising results from an initial human trial in which patients with se-
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vere head injury (GCS ≤ 8) were treated
with the oxygen radical scavenger superoxide dismutase combined with polyethylene glycol,195 free radical scavengers are
not ready today for use at, or near, the
point-of-wounding.
Antibiotic prophylaxis for central
nervous system wounds
The prevention of infection of wounds of
the central nervous system is very important because such infections can rapidly
result in meningitis, cerebritis, abscess
formation and even death. Unfortunately,
the efficacy of prophylactic antibiotic administration at, or near, the point-ofwounding, is unproven. Israeli data from
the Yom Kippur war even suggests that
the prophylactic use of antibiotics might
not only select for gram negative and
mixed microbial infections but may actually increase the overall risk of wound
infection.196
Although antibiotic prophylaxis in neurosurgical practice is not only very common
but is considered the standard of care by
many, the strength of evidence from civilian studies that proves that prophylactic
antibiotics are effective at reducing the
risk of infection from operations and
wounding is limited.
Savitz et al., advocates for antibiotic prophylaxis in neurosurgery admit, in their
2003 meta-analysis, that “To date, individual studies have not demonstrated a
significant benefit for prophylactic antibiotic therapy in spinal operations.”197(pp.2435)
But they go on to point out that, in their
meta-analysis, pooled infection rates were
2.2% (10 of 451 patients) with antibiotics
and 5.9% (23 of 392 patients) without antibiotics. The pooled odds ratio in their
meta-analysis was 0.37 (95% confidence
interval, 0.17-0.78), favoring antibiotic
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Clifford C. Cloonan, MD
treatment (P < 0.01). They concluded that
prophylactic antibiotic therapy is beneficial for spinal surgery, even when expected infection rates without antibiotic
treatment are low; and the rate of infection
in combat casualties with CNS injuries is
certainly much higher than that occurring
in planned surgeries.
During the Vietnam conflict sepsis, particularly in the setting of extensive burns
or penetrating trauma to central nervous
system, was the major cause of mortality
in rear echelon hospitals.198 The higher
the risk of infection the greater the likely
benefit of prophylactic antibiotic administration.
A number of double and single blinded
studies199-204 have been done that suggest
that antimicrobial prophylaxis reduces the
rate of wound infection following craniotomy. The recommendation of the 1988
U.S. edition of the NATO War Surgery
Manual205 regarding antibiotic prophylaxis
for combat casualties with CNS injuries, is
that, although the efficacy of prophylactic
antibiotics has not been proven, “intravenous antibiotics should be administered at
meningeal doses for one week.” Based
upon the currently available evidence such
a policy seems reasonable, especially in
the case of penetrating central nervous
system injury, and should probably be implemented without long delay. The only
question is which antibiotic should be
used for prophylaxis of CNS combat injury?
For combat wounds in general, cefoxitin,
was initially recommended by Butler and
Hagmann206 but prior to Operation Enduring Freedom Butler and O’Connor examined the concept of prophylactic antibiotic
administration by Special Operations
Forces medics and concluded that prophylactic administration of cefotetan, par-
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enterally,or gatifloxacin orally, were better
choices.207 Their recommendation lead to
a U.S. Army Special Operations Command policy of pre-hospital prophylactic
antibiotic administration by SOF medics
and these antibiotics were issued to SOF
medics for this purpose during Operations
Enduring Freedom and Iraqi Freedom.
Unfortunately cefotetan has poor penetration into the CSF and it is generally not
recommended for prophylaxis of CNS
injury. A better choice for antimicrobial
prophylaxis of combat caused CNS injuries is ceftriaxone.
Opponents of antibiotic prophylaxis argue
that great emphasis should be placed on
aseptic technique and wound care because
the administration of antibiotics alone will
not compensate for inattention to detail;207
they certainly have a point. The emphasis
in the training of pre-hospital personnel
should be on minimizing wound contamination and speedy evacuation to surgical
care. At best antibiotics are an adjunct to
good wound care not a substitute. It would
be ideal if a study were conducted to assess the efficacy of prophylactic antibiotic
administration prior to there being a Department of Defense-wide implementation
of a policy of prophylactic pre-hospital
antibiotic administration but this seems
unlikely.
Maintaining Adequate Oxygen
Delivery to the Brain-Injured
Casualty
The brain lies in a rigid container that has
a fixed volume of approximately 1500
cm3. Within this fixed space lie the parenchyma of the brain (approx. 80% of the
total volume), cerebral spinal fluid, and
blood (remaining 20%). Because the cranium is a rigid container, any increase in
one component must come at the expense
of one or more of the other components. If
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Clifford C. Cloonan, MD
trauma produces swelling of the brain or
an intracerebral hematoma, some cerebral
spinal fluid (CSF) and blood are excluded
from the space.
When the swelling and/or hematoma are
sufficiently large and no more CSF can be
excluded from the space, intracranial pressure rises and the flow of blood into the
brain slows and eventually stops. As cerebral blood flow drops, oxygen delivery to
brain cells drops, and when the threshold
is crossed where insufficient oxygen is
being delivered to meet cerebral metabolic
needs, ischemia, and eventually infarction,
occur.209
Through the mechanism of autoregulation,
primarily achieved by altering cerebral
vascular resistance, the body is able to
maintain a constant delivery of oxygen to
the brain despite a significant drop in
blood pressure or a significant rise in intracranial pressure (ICP). As intracranial
pressure rises, if the body is able to raise
the blood pressure, it does so in order to
maintain a cerebral blood flow great
enough to prevent irreversible neuronal
damage (> 18-20 mL/100 g brain tissue/min is the critical amount of blood
flow needed to deliver enough oxygen to
meet the minimal metabolic needs of the
brain). This is the Cushing response, i.e.,
increased ICP leading to hypertension and
a reflexive bradycardia. Cerebral blood
flow is equal to the cerebral perfusion
pressure, or mean arterial pressure (MAP)
minus ICP, divided by the cerebral vascular resistance.
(Cerebral blood flow) = (Cerebral perfusion pressure)
= (MAP-ICP) ÷ (Cerebral vascular resistance)
Under normal conditions, ICP is minimal
(0-10 mm Hg) so CPP is essentially equal
to MAP. In serious head trauma, the ICP
may increase enough to reduce the CPP to
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zero. Thus, a decrease in MAP and/or an
increase in ICP can result in decreased
cerebral blood flow.210 The critical issue in
the management of patients with serious
head injury is not intracranial pressure but
rather the delivery of sufficient oxygen to
meet cerebral metabolic needs. When efforts to reduce ICP reduce oxygen delivery, seriously brain injured patients may
have worse outcomes even if ICP is reduced. Measures that improve oxygen delivery to an injured brain include the following:
1. Maintaining MAP > 70 mm Hg
2. Ensuring an adequate amount of
functional hemoglobin
3. Optimizing oxygenation and ventilation
4. Ensuring that oxygen can be offloaded at the cellular level
5. Preventing and/or reducing cerebral edema
Measures that focus on treating elevated
ICP but also reduce cerebral blood flow
may be necessary if herniation is imminent, but depriving an ischemic brain of
oxygen to prevent herniation may result in
brain death.
Another way to ensure that sufficient oxygen is supplied to meet demand is to reduce demand. Preventing increases in the
cerebral metabolic requirement for oxygen
by preventing elevations in temperature
(or by inducing mild hypothermia), preventing and/or rapidly treating seizures,
and avoiding hyperglycemia are the most
commonly agreed-upon methods. Lowering the cerebral metabolic rate by prophylactically inducing a barbituate coma,
however, is more controversial. Despite
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Clifford C. Cloonan, MD
some theoretical advantages to the use of
prophylactic barbituate coma in treating
severely head-injured patients, it does not
appear to be beneficial in improving outcome211 and should not be attempted at or
near the point of wounding.
Elevation of the head has long been advocated in the prehospital treatment of headinjured patients. Despite this practice having been recently challenged on the
grounds that elevation of the head leads to
decreased cerebral perfusion pressure
studies by Feldman et al.212 and Hickey &
Sloan.139 have shown that head elevation
from 0° to 30° reduces intracranial pressure without producing any significant
change in cerebral perfusion pressure,
cerebral blood flow, cerebral metabolic
demand for oxygen, or cerebral vascular
resistance. Based upon these findings patients being treated for serious head injury
at or near the point of wounding should
have the head of the litter elevated by 15°
to 30° unless the patient is in shock that is
unresponsive to hemorrhage control and
fluid resuscitation.
Appropriate prehospital measures aimed at
minimizing the cerebral metabolic rate
that can, and should, be undertaken for the
seriously head-injured casualty include
controlling fever and other causes of elevated temperature (even mild hypothermia
has been shown to be protective in
ischemic brain injury),213 and control of
agitation and seizure activity.214
Mannitol and hypertonic saline can be
used individually to control cerebral
edema at or near the point of wounding.
Mannitol has long been used to control
intracerebral pressure and brain swelling
in patients with serious head injury. Recently two relatively large blinded, randomized, controlled, multi-center trials
conducted by Cruz et al. have looked at
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the efficacy of high dose mannitol in the
treatment of patients with blunt traumatic
subdural hematomas215 and traumatic intraparenchymal temporal lobe hemorrhages.216
Both of these studies demonstrated significant decreases mortality and morbidity
when a standard early initial bolus of 0.6 –
0.7 grams mannitol/kilogram body weight
mannitol was followed by an additional
bolus of 0.6 – 0.7 gm/kg if no pupillary
widening and up to 1.2 to 1.4 gm/kg if
pupillary widening was present. These
studies differ from earlier findings of no
benefit or even possible harm associated
with either repeated dosing with the use of
doses higher than .25 g/kg.217 If the Cruz
study findings of dramatic benefit from
high dose mannitol are confirmed by additional studies and especially if benefit is
shown from pre-hospital administration of
high dose mannitol then it would seem
reasonable to recommend the use of high
dose mannitol (1.4 gm/kg) to treat serious
blunt head injured combatants at or near
the point of wounding.
There is increasing interest in the use of
hypertonic saline both to treat hemorrhagic shock and cerebral edema. The use
of hypertonic saline alone, and combined
with dextran, has been studied extensively
for these indications.218-229
Although hypertonic saline is effective at
reducing cerebral edema and intracranial
pressure, and improving cerebral blood
flow, there is no definitive evidence it is
responsible for improved outcomes in
head injured patients.229 Most studies
comparing the efficacy of hypertonic saline with mannitol suggest a similar efficacy in terms of reduced intracranial pressure but indicate that mannitol may last
longer. Qureshi & Suarez,229 in their recent extensive review of the use of hyper-
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Clifford C. Cloonan, MD
tonic saline to treat cerebral edema and
intracranial hypertension, note that the
following adverse effects have been associated with the use of hypertonic saline:
•
•
•
•
•
Electrolyte abnormalities
Bleeding diatheses
Phlebitis
Cardiac failure
Central pontine myelinolysis and
rebound intracranial hypertension
(unproven but possible)229
With a low frequency of significant side
effects and with the majority of studies
showing a definite reduction in intracranial pressure following the administration
of hypertonic saline, it seems reasonable
to recommend the use of hypertonic saline
for the treatment of seriously head injured
patients at or near the point of wounding
when (and if) it is approved for use. The
use of hypertonic saline as a single resuscitative fluid for prehospital use in the
treatment of hemorrhagic and burn shock
and head injury patients is discussed at
length in the Circulation section.
High glucose levels should be avoided.
Specifically, patients with head injury
should not be resuscitated with glucosecontaining solutions and patients with altered mental status of unknown etiology
should not be reflexively given 50% glucose in water unless hypoglycemia has
been confirmed. High glucose levels may
aggravate ischemic injury by increasing
lactic acidosis and contributing to cerebral
edema.230-233 The goal in head-injured patients is to maintain blood sugar levels
between 100 and 150 mg/dL. In practical
terms, at or near the point of wounding,
this simply means that previously healthy
combat troops who may have serious head
injury should not be given glucosecontaining solutions.
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Hyperventilation
Although falling into disfavor, hyperventilation continues to be used by some to
treat patients with traumatic brain injury.
Ghajar et al. found in their survey of 277
medical centers specializing in neurotrauma that hyperventilation was used in
the treatment of intracranial hypertension
for most patients in 83% of the center surveyed.233 Despite this continued use the
evidence supporting the efficacy of hyperventilation is limited.
The important question is not whether hyperventilation reduces intracranial pressure, because it most certainly does, at
least acutely (but even this benefit is lost
after a few hours); it does so by reducing
cererbral arteriolar diameter (CO2 reactivity of cerebral arterioles) and by secondarily reducing cerebral blood flow.234 The
important question is, “Does hyperventilation reduce mortality and improve neurologic outcomes in head-injured patients?” There is little evidence to suggest
that it does and some evidence that, in
some circumstances, it actually increases
mortality and worsens neurologic outcomes (i.e. prolonged hyperventilation).235-237
Most important is not the intracranial
pressure but rather the
(1) Amount of oxygen the brain needs
(cerebral metabolic rate),
(2) Amount that is actually delivered,
and
(3) Ability of the brain to use the oxygen
that is delivered.
Cerebral oxygen content is dependent
upon cerebral blood flow, oxygen content
in the cerebral blood (primarily deter-
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Clifford C. Cloonan, MD
mined by hemoglobin content), and ability of the brain to extract the available
oxygen (oxygen-hemoglobin dissociation
curve). By increasing cerebrovascular resistance through hypocarbic vasoconstriction hyperventilation reduces cerebral
blood flow and secondarily reduces ICP.
Unfortunately this reduced ICP comes at
the cost of decreased oxygen delivery to
already ischemic gray matter. Hyperventilation reduces cerebral oxygen delivery
both by reducing cerebral blood flow and
by inducing an alkalemia that shifts the
oxygen-hemoglobin dissociation curve to
the left and reduces the ability of hemoglobin to off-load oxygen at the cellular
level.
The 1995 recommendation of the Joint
Section on Neurotrauma and Critical Care,
approved by the Boards of the American
Association of Neurological Surgeons and
Congress of Neurological Surgeons, states
that hyperventilation should not be used
prophylactically "…during the first 24
hours after severe traumatic brain injury…because it can compromise cerebral
perfusion during a time when cerebral
blood flow is reduced."179, 238 A somewhat
contrary position taken by Stocchetti &
Maas et al., in a recent review of hyperventilation for head injured patients,
states, “Our opinion is that the careful use
of hypocapnia for the short-term control of
raised ICP remains a useful…”239 In sum
it is certainly reasonable to limit the aggressiveness and duration of any hyperventilation that is done to treat intracranial
hypertension.
Evacuation of Head-Injured Patients
It has been known for many years that
expert neurosurgical care is critical to ensure optimal outcomes for head-injured
patients. As long ago as 1939 Jefferson
noted that, "…the mortality of head
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wounds is distinctly lower in the hands of
those who understand them…It is only too
easy to increase damage to the nervous
system by injudicious operating, and so to
leave the community's charge a permanently crippled individual."147(p.82)
Balancing the need to get head-injured
patients to the care of a neurosurgeon with
the small number of such specialists has
long been a challenge. Placing neurosurgeons far forward in the evacuation chain
creates critical shortages elsewhere and
leads to inefficient use of their specialized
talents. Placing them in centralized facilities far in the rear, however, excessively
prolongs the time it takes a head-injured
patient to reach this specialized level of
care. A variety of solutions to this problem
have been tried, but the best seems to be a
combination of placing neurosurgeons
mid-way in the evacuation chain and then
moving them and their team around to
areas of active or anticipated combat.17(pp.40-43), 76(pp. 378-379,387-389,392),147(p.52)
In the modern military neurosurgical record there appears to be an inconsistency
as to the impact of travel time on the morbidity and mortality of the head trauma
victim. Some sources indicate that such
patients "travel well,"17 (pp.101-102),147 (p.384)
while elsewhere the need for rapid transport and minimizing the time from wounding to neurosurgical care is emphasized.147
(p.52)
This is probably explained by the differences between types of head injury.
Patients sustaining serious blunt head
trauma are at much greater risk of developing an expanding intracranial hematoma
with increasing intracranial pressure than
are those sustaining penetrating head
trauma (at least those that survive to receive medical care).17 (p.102)
There is no question that when there is an
expanding hematoma and increasing in-
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Clifford C. Cloonan, MD
tracranial pressure, increased length of
time to surgery increases the likelihood of
death or permanent disability. In patients
with an acute subdural hematoma, Seelig
et al. found a fourfold increase in the mortality rate if surgery to evacuate the hematoma was delayed 4 hours or more after
injury compared with those patients who
had surgery within 2 hours.240, 241 Conversely, those with penetrating head injuries who have survived the immediate
post-injury period appear to tolerate long
transport reasonably well.
Any trained general surgeon can perform
surgical decompression of an expanding
intracranial hemorrhage when the location
of the hematoma is known. Unfortunately,
the only currently available means for accurately localizing an intracranial hematoma is computerized axial tomography.
Although weight is not an issue in civilian
health care, this piece of equipment is so
heavy that it is found no further forward
than a combat support hospital. If a new
portable, lightweight, durable, and easily
used device were introduced that could
localize an intracranial hematoma, it
would then be possible, far forward, to
sort head-injured patients into those who
can tolerate a long transport from those
who need early decompression by a general surgeon.
Making the appropriate evacuation decision is of critical importance in headinjured patients. Over-evacuation of patients sustaining minor closed-head injuries leads to a drain on forward combat
power that, as our army shrinks in size,
must be prevented at all costs.
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During World War II it was noted that
after such a patient was evacuated out of
the forward areas "an early return to duty
was unlikely."17(p.102) Wounds of the scalp
present a particular dilemma in that the
general recommendation is that, "Every
wound of the scalp must be regarded as a
possible penetrating wound until the presence of foreign bodies within the cerebrum
are ruled out with roentgenograms"17(p.102)
and "…no scalp wound is so trivial that it
should not be regarded as potentially serious,"147(p.84) yet minor scalp wounds can
and should be cared for in the forward,
prehospital environment, followed by a
quick return to duty. Mechanism of injury
can often be used to sort out those patients
with simple, uncomplicated, scalp injuries
from those with a penetrating scalp injury
or serious underlying injury. An effective,
lightweight, durable, and easy to use diagnostic tool to help differentiate between
these groups of patients would also be
very helpful.
It certainly continues to be the case that
patients who need the services of a neurosurgeon do best when evacuated directly
to a facility with neurosurgical capability
unless another more pressing injury takes
precedence. As well stated by Jolly in
1938, "Wounds of the head do not mix
well with other casualties in the rota for
operation…if they take their turn on the
same table with injuries of other regions
they come either to be operated upon by
those without the necessary knowledge
and ability, or they hold back other serious but more expeditiously dealt with injuries to their disadvantage."147(p.52)
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Clifford C. Cloonan, MD
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Summary
Penetrating and blunt head and neck
wounds injuries, while relatively uncommon in combat casualties, are disproportionately common relative to body surface
area and have a disproportionately high
morbidity and mortality. Although penetrating injuries predominate as the mechanism of injury in combat-caused head and
neck wounds, blunt trauma is becoming
relatively more common. Despite considerable advances in trauma care the morbidity and mortality of head and neck
wounds remains high.
In the forward combat areas little can be
done for casualties with such injuries and
sorting out minor head and neck injuries
from those requiring more advanced care
is problematic even for physicians, much
less combat medics. New, lightweight,
durable, and easy-to-use tools capable of
effectively sorting out these categories of
patients should be a high priority for the
military medical research and development community.
Combat-caused neck injuries, both penetrating and blunt, appear to be different
from their civilian counterparts in terms of
structures injured and likelihood of instability. Although any discussion about cervical spine instability is problematic because a consistent definition of “instability” is lacking in the literature, it appears
that combat casualties who survive a penetrating neck wound are considerably less
likely to have an “unstable” cervical spine
than civilian patients with anatomically
similar blunt trauma injuries.
There is even some suggestion in the literature that casualties who survive a lowvelocity penetrating wounding of the neck
are more likely to have spinal cord and
“unstable” injuries than casualties who
survive high-velocity bullet wounds of the
neck (a significant portion of this difference no doubt being due to a higher rate of
survival in low-velocity wounding). Although casualties with blunt neck trauma
and cervical spine instability can certainly
sustain spinal cord injury if they are handled injudiciously, it would seem that the
risk of this, in a prehospital combat setting, may be overstated especially if the
casualty is awake, responsive, and able to
protect his or her own cervical spine.
How to best manage neck-injured casualties at or near the point of wounding is
problematic. There is significant controversy, even in civilian EMS literature, regarding the appropriate management of
patients with these injuries. Even if there
were a general consensus regarding the
appropriate prehospital management of
civilian patients with neck injuries, the
differences between civilian and combat
circumstances would render the decision
mostly irrelevant to the management of
neck-injured combat casualties. Not only
are there significant differences between
typical civilian and combat-related neck
injuries in terms of likelihood of spinal
cord injury and instability, virtually all
aspects of prehospital combat casualty
care are different in ways that alter the
risk-benefit ratio of the typical civilian
EMS approach to the management of such
casualties.
In civilian settings, EMS supplies are
transported to the scene of the injury by
vehicle while in most combat situations
medical supplies are carried on the backs
of combat medics. Backboards are out of
the question and even cervical collars
might be left behind in favor of more field
dressings.
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
The care environment is different as well.
In civilian settings, it is rare that patients
remain at continued risk of serious injury
following the initial wounding and even
rarer that prehospital personnel are seriously at risk while attempting to render
initial care. During initial evacuation,
however, combat casualties must often be
left unattended (or without skilled attendance) during transport. Evacuation times
are usually significantly longer in combat
than in civilian settings.
All of these differences increase the risk
associated with applying the standard
treatment of civilian neck-injured casualties to combat casualties, i.e., complete
immobilization on a long backboard.
Combat casualties thus treated would be
exposed to serious risk of aspiration, impaired ventilation, and pressure sores and
would be unable to protect themselves or
assist in any way should there be an attack
on their evacuation vehicle.
Although it is common practice for combat medics to carry a rigid cervical collar
to treat combat casualties with a presumed
high risk of cervical spine injury, no data
supports this practice. It is possible that, in
sum, there may be more risk than benefit
from applying just a rigid cervical collar
when compared to not applying one.
However, rather than abandon this apparently reasonable practice because of the
lack of supportive evidence, it would seem
sensible to continue to apply a cervical
collar to those combat casualties at relatively high risk of cervical spine injury. A
study to determine exactly what are the
risks and benefits of isolated cervical collar application to casualties with potential
cervical spine injury needs to be done.
When the mechanism of injury is blunt
and significant (fall from a height, motor
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vehicle or aircraft crash, etc…) and especially when the casualty has a complaint
of neck pain and/or there are neurologic
findings consistent with spine injury, spine
immobilization should be carried out to
the extent possible with available supplies
and appropriate for the tactical and
evacuation circumstances.
It is essential that every forward area
medical provider recognize that any casualty restrained in a supine position is at
risk of aspiration, impaired ventilation,
and pressure sores. Further, they are entirely at the mercy of others and the circumstances of the moment. During
evacuation, an attendant skilled in basic
airway management must be continually
in attendance of any casualty strapped
down or otherwise unable to protect his or
her own airway.
To prevent pressure sores, all hard objects
must be removed from the pockets and
from behind the casualty and, especially if
the transport is long, the weight of the
casualty should be periodically shifted.
These are all reasonable guidelines that
should be provided to prehospital combat
medical personnel. Even in this selected
population, the likelihood of prehospital
care converting a spine injured, cordintact, patient into a cord-damaged patient
is very small (but certainly not zero). The
risk of this occurrence has probably been
seriously overstated in the literature and is
probably even lower in a population of
young, previously healthy, unintoxicated
military combatants.
When the mechanism of injury is penetrating, the primary management focus must
be on ensuring that the airway remains
patent, that the patient is adequately ventilating, and that hemorrhage is controlled.
Speed of evacuation to resuscitative sur-
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Clifford C. Cloonan, MD
gery is probably the key factor in survival
of such patients. The application of advanced airway management techniques by
prehospital personnel to casualties with
neck injuries, especially penetrating neck
injuries, carries significant risk and should
be avoided unless unequivocally indicated
and the care provider is trained and experienced in the technique(s). Specific
efforts to secure the cervical spine of
casualties with penetrating neck wounds
are likely to result in greater harm than
benefit. This is not to suggest that the cervical spine should be entirely disregarded,
just that concerns for the cervical spine
should not dictate management. Certainly,
if a casualty complains of increased pain
or develops new neurologic symptoms
with movement, reasonable and appropriate measures should be taken to stabilize
the spine.
The civilian controversy regarding clinical
“clearing” of the cervical spine, either in
the field, or in an emergency department,
is probably not directly relevant to prehospital combat casualty care. In most
circumstances at or near the point of
wounding, casualties will “clear” their
own cervical spine if able to do so. Absent
any specific guidelines, most combat medics will use common sense to “clear” most
casualties with neck injuries who come to
their attention. For this reason, it would
probably be useful to provide to combat
medics simple guidelines for making a
decision regarding which casualties to return to duty, which to evacuate, and which
would likely benefit from cervical spine
immobilization.
If it is clear that a casualty with a blunt
trauma mechanism has sustained spinal
cord injury, the current guidelines are to
administer high-dose methylprednisolone
as soon as possible. In most situations, this
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should be done at the level of the Battalion
Aid Station rather than in the field.
For head injured casualties a patent airway, adequate ventilation, and control of
all controllable hemorrhage are the main
priorities. Casualties with serious head
injuries should be transported in the lateral
recumbent position or in the prone position with the head turned to the side. If it
is necessary, for any reason (such as cervical spine immobilization), to transport
such casualties in a supine position an attendant with ready access to suction and
skilled in airway management must be
present throughout the transport.
Early and adequate ventilation, oxygenation and cerebral perfusion are critical.183
All controllable hemorrhage should be
controlled. Contrary to the approach for
most patients with uncontrolled internal
bleeding, head injured patients should be
fluid resuscitated to maintain a systolic
blood pressure above 90 mm of mercury.
In casualties with significant hemorrhage
and with altered mental status, head injury, not hypovolemia, should be considered the cause until proven otherwise. As
noted in the circulation chapter, most
combat casualties in hemorrhagic shock
have clear mental status until cerebral perfusion pressure drops below 70 mm of
mercury.
In managing the potentially head injured
casualty at, or near, the point-ofwounding, the job of the pre-hospital
combat care provider is to identify which
casualties may have sustained serious
head injury, and decide which need urgent
evacuation to the care of a neurosurgeon
and which can be safely returned to duty.
As circumstances permit there should be a
low threshold for rapid evacuation of head
injured casualties. Guidelines developed
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Immediate Care of the Wounded
Clifford C. Cloonan, MD
to minimize head CT use in trauma victims with minor head injuries may be useful in developing head injury evacuation
guidelines and in making return-to-duty
decisions.184, 186
The critical issue in the management of
patients with serious head injury is delivery of sufficient oxygen to meet cerebral
metabolic needs. The forward health care
provider achieves this by maintaining an
adequate blood pressure, preventing all
preventable blood loss, optimizing oxygenation and ventilation, insuring that
oxygen can be off-loaded at the cellular
level by avoiding alkalosis from excessive
hyperventilation, and preventing and/or
reducing cerebral edema by avoiding
overhydration (especially with hypotonic
solutions). The current recommendation is
that hyperventilation should not be used
prophylactically.179, 238
Outcomes of head injured patients can
also be improved by reducing cerebral
metabolic demand. Temperature elevation
should be avoided, seizures prevented
and/or rapidly treated, and hyperglycemia
avoided. The head of the litter of head injured casualties should elevated by 15 to
30 degrees unless the patient is in shock
unresponsive to hemorrhage control and
fluid resuscitation.138, 212, 214 Mannitol and
hypertonic saline are both capable of reducing cerebral edema 216-219, 222-224, 226-229,
242
but it remains unclear how much either
of these agents contributes of overall survival of head injured patients.229 It is still
seems reasonable to recommend the use of
Mannitol at the level of a battalion aid
station to treat seriously head injured patients.
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priate enroute care, can usually tolerate
relatively long evacuation.17(pp101-102),76 (p384)
Patients with serious blunt head trauma
appear to do less well if evacuation is
lengthy.17 (p102),147 (p52) When there is an
expanding hematoma and increasing intracranial pressure the head injured casualty should be evacuated to the closest
surgeon who can localize the lesion and
perform surgical decompression. Patients
who need the services of a neurosurgeon
do best when evacuated directly to a facility with neurosurgical capability unless
another more pressing injury takes precedence.147 (p52)
Although clear scientific proof is lacking
to support the efficacy of prophylactic
antibiotic administration by pre-hospital
personnel to prevent central nervous system wound infections, the weight of the
available evidence supports such a policy.
The specific antibiotic selected for this
purpose should have low risks, a long
half-life, should readily penetrate into the
CNS, should be effective against common
CNS pathogens, and should not have any
special handling considerations, such as a
requirement for refrigeration.
Combat casualties with penetrating head
wounds who survive the initial wounding
apparently “travel well” and, with appro-
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Clifford C. Cloonan, MD
Disability
References
1.
Gibbs M, Jones A. Cervical spine injury: A state-of-the-art approach to assessment and
management. Emerg Med Pract. 2001;10:1-24.
2.
Beatty W. The death of Lord Nelson: The authentic narrative. 4th ed. London, UK: Stobart
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